ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (400)
  • Blackwell Publishing Ltd  (400)
  • American Institute of Physics (AIP)
  • 1995-1999  (400)
  • 1990-1994
  • 1980-1984
  • 1925-1929
  • 1998  (222)
  • 1997  (178)
  • Medicine  (400)
Collection
  • Articles  (400)
Source
Publisher
Years
  • 1995-1999  (400)
  • 1990-1994
  • 1980-1984
  • 1925-1929
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Nucleoside diphosphate kinase: role in bacterial growth, virulence, cell signalling and polysaccharide synthesis (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Nucleoside diphosphate kinase (Ndk) is an important enzyme that generates nucleoside triphosphates (NTPs) or their deoxy derivatives by terminal phosphotransfer from an NTP such as ATP or GTP to any nucleoside diphosphate or its deoxy derivative. As NTPs, particularly GTP, are important for cellular macromolecular synthesis and signalling mechanisms, Ndk plays an important role in bacterial growth, signal transduction and pathogenicity. Specific examples of the role of Ndk in regulating growth, NTP formation and cell surface polysaccharide synthesis in two respiratory tract pathogens, Pseudomonas aeruginosa and Mycobacterium tuberculosis, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00846.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The BvgAS virulence control system regulates type III secretion in Bordetella bronchiseptica (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The BvgAS signal transduction system in Bordetella spp. mediates a transition between infectious (Bvg+) and non-infectious (Bvg−) phases by sensing environmental conditions and regulating gene expression. Using differential display, arbitrary-primed polymerase chain reaction (PCR), we identified a gene expressed in the Bvg+ phase of Bordetella bronchiseptica that shows a high degree of sequence similarity to a locus involved in providing energy for type III secretion in pathogenic Gram-negative bacteria (yscN in Yersinia spp.). We determined that the expression of this homologue in B. bronchiseptica (designated bscN ) is regulated by bvg. Several open reading frames surrounding the bscN locus also show sequence similarity to loci encoding type III secretion apparatus components in other bacteria. An in-frame deletion of bscN in B. bronchiseptica leads to decreased secretion of several proteins, decreased cytotoxicity towards cultured cell lines and a defect in causing tyrosine dephosphorylation of specific proteins in infected cells in vitro. The deletion strain also revealed that bscN-mediated secretion is required for persistent colonization of the trachea in a rat infection model. Loci encoding type III secretion homologues were identified in four strains of B. pertussis and two strains of B. parapertussis. B. pertussis strain 18323 and an ovine isolate of B. parapertussis show significant transcription of the genes in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00850.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Interplay between global regulators of Escherichia coli : effect of RpoS, Lrp and H-NS on transcription of the gene osmC (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The transcription of the osmC gene of Escherichia coli is regulated as a function of the phase of growth. It is induced during the decelerating phase, before entry into stationary phase. osmC expression is directed by two overlapping promoters, osmCp1 and osmCp2. osmCp2 is mainly transcribed by E-σs, the RNA polymerase using the σs (RpoS) sigma factor, and is responsible for the growth phase regulation. Transcription from osmCp1 is independent of σs. The leucine-responsive protein (Lrp) has been shown to bind the osmC promoter region in band shift experiments. In vivo analysis using osmC–lacZ transcriptional fusions demonstrated that Lrp affects the expression of both promoters. It represses the transcription of osmCp1 and activates the transcription of osmCp2 by E-σs. An absence of Lrp results in an increase in the amount of RpoS during exponential growth in minimal medium. The nucleoid-associated protein H-NS also represses osmC transcription from both promoters. However, this happens through different mechanisms. The effect on osmCp2 is probably mediated by the increase in σs concentration in the cytoplasm of hns− mutants, while the effect on osmCp1 is independent of σs. No binding of H-NS to the promoter region DNA could be detected, indicating that the effect on osmCp1 could also be indirect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00855.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The structure of an ECF-σ-dependent, light-inducible promoter from the bacterium Myxococcus xanthus (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Expression of the Myxococcus xanthus gene crtI is controlled by a light-inducible promoter. The activity of this promoter depends on CarQ, a σ factor of the extracytoplasmic function (ECF) subfamily. Here, we show that the minimum DNA stretch reproducing normal expression of crtI extends from a few bases upstream of the −35 position to a site well downstream of the transcriptional start. The downstream DNA contains an enhancer-like element that remains active when displaced upstream of the promoter. Experimental evidence is provided for the activity of the crtI promoter being critically dependent on a pentanucleotide sequence centred at the −31 position. The similarity of this sequence with the consensus for ECF-σ-dependent promoters from other bacteria is discussed. The activity of the crtI promoter also depends on certain basepairs at the −10 region. Hence, the operation of ECF-σ-factors seems to require binding to two different DNA sites, although the −10 sequences of different ECF-σ-dependent promoters are unrelated to one another, and the ECF-σ-factors themselves lack the conserved domain known to mediate binding of other σ-factors to the −10 DNA site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01129.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Pmt1 mannosyl transferase is involved in cell wall incorporation of several proteins in Saccharomyces cerevisiae (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We constructed hybrid proteins containing a plant α-galactosidase fused to various C-terminal moieties of the hypoxic Srp1p; this allowed us to identify a cell wall-bound form of Srp1p. We showed that the last 30 amino acids of Srp1p, but not the last 16, contain sufficient information to signal glycosyl-phosphatidylinositol anchor attachment and subsequent cell wall anchorage. The cell wall-bound form was shown to be linked by means of a β1,6-glucose-containing side-chain. Pmt1p enzyme is known as a protein-O-mannosyltransferase that initiates the O-glycosidic chains on proteins. We found that a pmt1 deletion mutant was highly sensitive to zymolyase and that in this strain the α-galactosidase–Srp1 fusion proteins, an α-galactosidase–Sed1 hybrid protein and an α-galactosidase–α-agglutinin hybrid protein were absent from both the membrane and the cell wall fractions. However, the plasma membrane protein Gas1p still receives its glycosyl-phosphatidylinositol anchor in pmt1 cells, and in this mutant strain an α-galactosidase–Cwp2 fusion protein was found linked to the cell wall but devoid of β1,6-glucan side-chain, indicating an alternative mechanism of cell wall anchorage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00660.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Differences in chromosome number and genome rearrangements in the genus Brucella (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have studied the genomic structure and constructed the SpeI, PacI and I-CeuI restriction maps of the four biovars of the pathogenic bacterium Brucella suis. B. suis biovar 1 has two chromosomes of 2.1 Mb and 1.15 Mb, similar to those of the other Brucella species: B. melitensis, B. abortus, B. ovis and B. neotomae. Two chromosomes were also observed in the genome of B. suis biovars 2 and 4, but with sizes of 1.85 Mb and 1.35 Mb, whereas only one chromosome with a size of 3.1 Mb was found in B. suis biovar 3. We show that the differences in chromosome size and number can be explained by rearrangements at chromosomal regions containing the three rrn genes. The location and orientation of these genes confirmed that these rearrangements are due to homologous recombination at the rrn loci. This observation allows us to propose a scheme for the evolution of the genus Brucella in which the two chromosome-containing strains can emerge from an hypothetical ancestor with a single chromosome, which is probably similar to that of B. suis biovar 3. As the genus Brucella is certainly monospecific, this is the first time that differences in chromosome number have been observed in strains of the same bacterial species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00661.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    A mechanical approach to the distribution and orientation of genes on genetic maps (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00669.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Isolation and analysis of xlnR, encoding a transcriptional activator co-ordinating xylanolytic expression in Aspergillus niger (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Complementation by transformation of an Aspergillus niger mutant lacking xylanolytic activity led to the isolation of the xlnR gene. The xlnR gene encodes a polypeptide of 875 amino acids capable of forming a zinc binuclear cluster domain with similarity to the zinc clusters of the GAL4 superfamily of transcription factors. The XlnR-binding site 5′-GGCTAAA-3′ was deduced after electrophoretic mobility shift assays, DNase I footprinting and comparison of various xylanolytic promoters. The importance of the second G within the presumed XlnR binding site 5′-GGCTAAA-3′ was confirmed in vitro and in vivo. The 5′-GGCTAAA-3′ consensus sequence is found within several xylanolytic promoters of various Aspergillus species and Penicillium chrysogenum. Therefore, this sequence may be an important and conserved cis-acting element in induction of xylanolytic genes in filamentous fungi. Our results indicate that XlnR is a transcriptional activator of the xylanolytic system in A. niger.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00666.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Distinct regions of the colicin A translocation domain are involved in the interaction with TolA and TolB proteins upon import into Escherichia coli (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Group A colicins need proteins of the Escherichia coli envelope Tol complex (TolA, TolB, TolQ and TolR) to reach their cellular target. The N-terminal domain of colicins is involved in the import process. The N-terminal domains of colicins A and E1 have been shown to interact with TolA, and the N-terminal domain of colicin E3 has been shown to interact with TolB. We found that a pentapeptide conserved in the N-terminal domain of all group A colicins, the ‘TolA box’, was important for colicin A import but was not involved in the colicin A–TolA interaction. It was, however, involved in the colicin A–TolB interaction. The interactions of colicin A N-terminal domain deletion mutants with TolA and TolB were investigated. Random mutagenesis was performed on a construct allowing the colicin A N-terminal domain to be exported in the bacteria periplasm. This enabled us to select mutant protein domains unable to compete with the wild-type domain of the entire colicin A for import into the cells. Our results demonstrate that different regions of the colicin A N-terminal domain interact with TolA and TolB. The colicin A N-terminal domain was also shown to form a trimeric complex with TolA and TolB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00667.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    RNase T is related to dnaQ and family C DNA polymerases (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00673.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Energy requirement for pullulanase secretion by the main terminal branch of the general secretory pathway (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The energy requirement for the second step in pullulanase secretion by the general secretory pathway was studied in Escherichia coli. In order to uncouple the two steps in the secretion pathway (across the cytoplasmic and outer membranes, respectively) and to facilitate kinetic analysis of secretion, a variant form of pullulanase lacking its N-terminal fatty acid membrane anchor was used. The transport of the periplasmic secretion intermediate form of this protein across the outer membrane was not inhibited by concentrations of sodium arsenate in excess of those required to reduce ATP levels to ≤10% of their normal value. Pullulanase secretion was inhibited by the protonophore carbonyl cyanide m-chlorophenyl hydrazone at concentrations which were similar to those reported by others to be required to prevent solute uptake or the export and processing of preproteins across the cytoplasmic membrane, but which were in excess of those required to fully dissipate the proton-motive force and to reduce lactose uptake to a significant extent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3451726.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Transcriptional regulation of the Yersinia pseudotuberculosis pH 6 antigen adhesin by two envelope-associated components (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Yersinia pseudotuberculosis pH 6 antigen mediates haemagglutination and adhesion to cultured mammalian cells. The synthesis of pH 6 antigen requires the products of the psaEFABC genes in both Yersinia pseudotuberculosis and Escherichia coli. In-frame deletion mutations of psaE and psaF caused defective haemagglutination. In contrast, we showed that the psaABC genes were sufficient for haemagglutination if they were expressed by a heterologous promoter. Environmental regulation of pH 6 antigen by temperature and pH occurs via regulation of the major pilus protein PsaA at the transcriptional level. Northern blot analyses indicate that the psaA transcript was absent in either psaE or psaF mutant strains. Primer extension analyses indicate that, in Y. pseudotuberculosis, the transcription of the psaE and psaF genes is constitutive. Alkaline phosphatase fusion studies confirm the topology prediction that PsaE and PsaF are both inner-membrane-associated proteins. PsaE consists of an N-terminal cytoplasmic domain, containing sequence similarity to transcriptional regulators found in two-component systems as well as to the Salmonella typhimurium HilA protein, with a C-terminal domain that is periplasmically localized. PsaF is predicted to be oriented with most of the protein in the periplasm, the hydrophobic N-terminus being either integrated in the inner membrane or cleaved as a signal peptide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3511719.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Ffh and FtsY in a Mycoplasma mycoides signal-recognition particle pathway: SRP RNA and M domain of Ffh are not required for stimulation of GTPase activity in vitro (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Mycoplasma mycoides contains a signal-recognition particle (SRP) composed of an RNA molecule and an SRP54 homologue (Ffh). We have now identified a mycoplasma homologue to the α subunit of the mammalian SRP receptor and Escherichia coli FtsY. The protein (MmFtsY) was expressed in E. coli and purified to homogeneity. MmFtsY has a weak intrinsic GTPase activity but GTP hydrolysis was markedly stimulated when it was combined with mycoplasma Ffh (MmFfh) and SRP RNA. Also, in the absence of SRP RNA GTPase activity was significantly enhanced. Furthermore, GTP hydrolysis was stimulated when MmFtsY was combined with the N-terminal GTPase domain (N+G) of MmFfh. These findings indicate that basic features of the GTPase activation mechanism are independent of the C-terminal M domain of the MmFfh protein. We propose that the activation is mediated to a large extent by contacts between the GTPase domains of the mycoplasma Ffh and FtsY proteins and that the contribution of the M domain and SRP RNA in the activation mechanism is mainly for modifying the conformation of the MmFfh GTPase domain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3551729.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    The cioAB genes from Pseudomonas aeruginosa code for a novel cyanide-insensitive terminal oxidase related to the cytochrome bd quinol oxidases (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The structural genes for the cyanide-insensitive terminal oxidase (CIO) of Pseudomonas aeruginosa were sequenced. The locus comprised two open reading frames, cioA and cioB, coding for gene products of 488 and 335 amino acid residues with predicted molecular masses of 54 241 and 37 016 Da respectively. These genes were encoded by a 2.7 kb transcript and probably comprise an operon. Upstream of a major transcriptional start site is a −10 promoter region and, approximately at nucleotides −50 and +13, there are sequences homologous to the binding site of the transcriptional regulator Anr. The deduced amino acid sequences of CioA and CioB are homologous to the cytochrome bd quinol oxidases of Escherichia coli and Azotobacter vinelandii. However, no cytochrome d-like signals were found in wild-type P. aeruginosa strains. An atypical cytochrome d-like signal was seen under low-aeration growth conditions but only in strains in which the cioAB genes were present on a high-copy-number plasmid. The appearance of these cytochrome d-like signals was not paralleled by a concomitant increase in CIO activity. These data support the hypothesis that the CIO of P. aeruginosa does not contain haem d. This raises the possibility that there is a family of bacterial quinol oxidases related to the cytochrome bd of E. coli that can differ in their haem composition from the E. coli paradigm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3561728.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Sequence requirements for the termination of rolling-circle replication of plasmid pT181 (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Most small multicopy plasmids of Gram-positive bacteria and many in Gram-negative bacteria replicate by a rolling-circle (RC) mechanism. The replication initiator proteins encoded by the RC plasmids and single-stranded bacteriophages of Escherichia coli have origin-specific nicking-closing activities that are required for the initiation and termination of RC replication. We have investigated the sequence requirements for termination of RC replication of plasmid pT181. The initiator nick site is located in the loop of a hairpin region (IRII) within the pT181 origin of replication. By mutational analysis, we have found that several nucleotides within the stem of IRII which are critical for the initiation activity are dispensable for termination of replication. We also demonstrate that nucleotides in the right arm of IRII, but not the left arm, are absolutely required for termination of RC replication. We have also identified specific nucleotides in IRII that are critical for its termination activity. The sequence of the right arm of the hairpin must be located downstream of the initiator nick site for termination, suggesting that termination requires a specific orientation of the initiator protein at the origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3641730.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Modulator protein RsbR regulates environmental signalling in the general stress pathway of Bacillus subtilis (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Bacillus subtilis responds to signals of environmental and metabolic stress by inducing over 40 general stress genes under the control of the σB transcription factor. σB activity is regulated post-translationally by a multicomponent network composed of two coupled partner-switching modules, RsbX-RsbS-RsbT and RsbU-RsbV-RsbW, each containing a serine phosphatase (X or U), an antagonist protein (S or V), and a switch protein/serine kinase (T or W). The upstream module (X-S-T) is required to transmit signals of environmental stress. In contrast, the downstream module (U-V-W) is required to transmit signals of energy stress as well as the environmental signals conveyed to it from the upstream module. Until now the function of the rsbR gene product was unknown. RsbR shares significant sequence similarity with the RsbS and RsbV antagonist proteins whose phosphorylation states control key protein–protein interactions within their respective modules. Here we present evidence that RsbR is associated with RsbS in the upstream, environmental-sensing module. To investigate RsbR function, we constructed deletion and point mutations within rsbR and tested their effects on expression of σB-dependent reporter fusions, both singly and in combination with other rsb mutations. To determine the possible interaction of RsbR with other Rsb proteins, we tested the ability of wild-type or mutant RsbR to activate transcription in the yeast two-hybrid system in conjunction with other Rsb regulators. On the basis of this genetic analysis, we conclude that RsbR is a positive regulator which modulates σB activity in response to salt and heat stress. Our data further suggest that: (i) RsbR influences the antagonist function of RsbS by direct protein–protein interaction; and (ii) this interaction with RsbS is likely controlled by the phosphorylation state of RsbR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3631732.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Analysis of the architecture of the transcription factor σN (σ54) and its domains by circular dichroism (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Enhancer-dependent transcription in bacteria requires the alternative transcription factor σN (σ54), which forms an RNA polymerase holoenzyme that binds promoters as a transcriptionally inactive complex. We have examined the structure of σN by circular dichroism (CD) analysis. The σN protein and its domains are well structured in the absence of the core RNA polymerase subunits or promoter DNA. Denaturation of σN by temperature as followed by changes in CD shows a concomitant loss of secondary and tertiary structures with a melting temperature of 36°C. The secondary structure displays a two-state melting curve with a second Tm of 85°C. The amino-terminal Region I activation domain together with the acidic Region II does not contribute to the two-state melting. In marked contrast, the integrity of the C-terminal DNA-binding domain is required for the two-state melting. Measurements of pKb also demonstrated that a C-terminal part of σN, but not regions I or I + II, is required for the structural integrity of σN at high pH. Measurements of pKa suggested that α-helical structures are important in σN for the establishment of tertiary structural elements. The tertiary structure near ultraviolet CD signals of σN do not require regions I or I + II but were strongly diminished by C-terminal truncation of σN. Promoter DNA binding resulted in aconformational change in σN, permitting the determination of a binding constant. A typical B-DNA conformation was adopted by the promoter DNA. Implications for the modular domain organization of σN, the function of C-terminal sequences, and domain communication and its role in activation of transcription are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3691738.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Transcriptional regulation of the macrophage-induced gene (gspA) of Legionella pneumophila and phenotypic characterization of a null mutant (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Expression of the global stress protein gene (gspA) is induced during the intracellular infection of macrophages and upon exposure of Legionella pneumophila to in vitro stress stimuli. Transcription of gspA is regulated by two promoters, one of which is regulated by the σ32 heat-shock transcription factor. We utilized a gspA promoter fusion to a promoterless lacZ to probe the phagososmal ‘microenvironment’ for the kinetics of exposure of intracellular L. pneumophila to stress stimuli. Expression through the gspA promoter was constitutively induced by approx. 16-fold throughout the intracellular infection, and occurred predominantly through the σ32-regulated promoter. Expression of the gspA promoter was induced approx. 4.5-fold, 5-, 11- and 9-fold upon exposure of L. pneumophila to heat shock, oxidative stress, acid shock, and osmotic shock, respectively. An isogenic insertion mutant of L. pneumophila in gspA (strain AA224) was constructed by allelic exchange in the wild-type strain AA200. Compared to in vitro-grown wild-type strain AA200, AA224 was more susceptible to all four in vitro stress stimuli. The wild-type phenotypes were restored to strain AA224 by complementation with a plasmid containing wild-type gspA. There was no difference between the wild-type strain and the gspA mutant in cytopathogenicity to U937 cells or in their kinetics of intracellular replication within macrophages and amoebae. However, compared to in vitro-grown bacteria, macrophage-grown and amoebae-grown AA200 and AA224 showed an equal and dramatic increase in resistance to in vitro stress stimuli. Our data showed that regardless of the capacity of L. pneumophila to subvert the microbicidal mechanisms of the macrophage, intracellular L. pneumophila is exposed to a high level of stress stimuli throughout the intracellular infection. Although the GspA protein is required for protection of the bacteria against in vitro stress stimuli, and is induced during intracellular multiplication, the loss of its function is probably compensated for by other macrophage-induced and stress-induced proteins within the intracellular environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3661739.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Studies on prolysostaphin processing and characterization of the lysostaphin immunity factor (Lif) of Staphylococcus simulans biovar staphylolyticus (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Lysostaphin is an extracellular glycylglycine endopep-tidase produced by Staphylococcus simulans biovar staphylolyticus ATCC1362 that lyses staphylococcal cells by hydrolysing the polyglycine interpeptide bridges of the peptidoglycan. Renewed analysis of the sequence of the lysostaphin gene (Iss), and the sequencing of the amino-terminus of purified prolysostaphin and of mature lysostaphin revealed that lysostaphin is organized as a preproprotein of 493 amino acids (aa), with a signal peptide consisting of 36 aa, a propeptide of 211 aa from which 195 aa are organized in 15 tandem repeats of 13 aa length, and a mature protein of 246 aa. Prolysostaphin is processed in the culture supernatant of S. simulans biovar staphylolyticus by an extracellular cysteine protease. Although prolysostaphin was staphylolytically active, the mature lysostaphin was about 4.5-fold more active. The controlled expression in Staphylococcus carnosus of Iss and Iss with deletions in the prepropeptide region indicated that the tandem repeats of the propeptide are not necessary for protein export or activation of Lss, but keep Lss in a less active state. Intracellular expressed pro- and mature lysostaphin exert staphy-lolytic activity in cell-free extracts, but do not affect growth of the corresponding clones. We characterized a lysostaphin immunity factor gene (lif) which is located in the opposite direction to Iss. The expression of lif in S. carnosus led to an increase in the serine/glycine ratio of the interpeptide bridges of peptidoglycan from 2 to 35%, suggesting that lysostaphin immunity depends on serine incorporation into the interpeptide bridge. If, in addition to lif, Iss is co-expressed the serine/glycine ratio is further increased to 58%, suggesting that Lss selects for optimal serine incorporation. Lif shows similarity to FemA and FemB
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2911657.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Catabolite repression of the Bacillus subtilis gnt operon exerted by two catabolite-responsive elements (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Catabolite repression of Bacillus subtilis catabolic operons is supposed to occur via a negative regulatory mechanism involving the recognition of a cis-acting catabolite-responsive element (cre) by a complex of CcpA, which is a member of the GalR-LacI family of bacterial regulatory proteins, and the seryl-phos-phorylated form of HPr (P-ser-HPr), as verified by recent studies on catabolite repression of the gnt operon. Analysis of the gnt promoter region by deletions and point mutations revealed that in addition to the ere in the first gene (gntR) of the gnt operon (credown), this operon contains another ere located in the promoter region (creup). A translational gntR-lacZ fusion expressed under the control of various combinations of wild-type and mutant credown and creup was integrated into the chromosomal amyE locus, and then catabolite repression of p-galac-tosidase synthesis in the resultant integrants was examined. The in vivo results implied that catabolite repression exerted by creup was probably independent of catabolite repression exerted by credown; both creup and credown catabolite repression involved CcpA. Catabolite repression exerted by creup was independent of P-ser-HPr, and catabolite repression exerted by credown was partially independent of P-ser-HPr. DNase I footprinting experiments indicated that a complex of CcpA and P-ser-HPr did not recognize creup, in contrast to its specific recognition of credown. However, CcpA complexed with glucose-6-phosphate specifically recognized creup as well as credown, but the physiological significance of this complexing is unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2921662.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    A two-gene ABC-type transport system that extrudes Na+ in Bacillus subtilis is induced by ethanol or protonophore (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A transposition mutant of Bacillus subtilis (designated JC901) that was isolated on the basis of growth inhibition by Na at elevated pH, was deficient in energy-dependent Na extrusion. The capacity of the mutant JC901 for Na -dependent pH homeostasis was unaffected relative to the wild-type strain, as assessed by regulation of cytoplasmic pH after an alkaline shift. The site of transposition was near the 3 -terminal end of a gene, natB, predicted to encode a membrane protein, NatB. NatB possesses six putative membrane-spanning regions at its C-terminus, and exhibits modest sequence similarity to regions of eukaryotic Na+/H+ exchangers. Sequence and Northern blot analyses suggested that natB forms an operon with an upstream gene, natA. The predicted product of natA is a member of the family of ATP-binding proteins that are components of transport systems of the ATP-binding cassette (ABC) or traffic ATPase type. Expression of the lacZ gene that was under control of the promoter for natAB indicated that expression of the operon was induced by ethanol and the protonophore carbonylcyanide p-chlorophenylhydrazone (CCCP), and, more modestly, by Na+, and K+, but not by choline or a high concentration of sucrose. Restoration of the natAB genes, cloned in a recombinant plasmid (pJY1), complemented the Na+-sensitive phe-notype of the mutant JC901 at elevated pH and significantly increased the resistance of the mutant to growth inhibition by ethanol and CCCP at pH 7; ethanol was not excluded, however, from the cells expressing natAB, so ethanol-resistance does not result from NatAB-dependent ethanol efflux. Transformation of the mutant with pJY1 did markedly enhance the capacity for Na+
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2951656.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    DnaA protein stimulates polA gene expression in Escherichia coli (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The polA gene of Escherichia coli encodes DNA polymerase I that is involved in DNA replication and repair. Despite the wide knowledge about structure and function of DNA polymerase I, there is little insight into the regulatory mechanisms involved in polA expression. DnaA is the initiator protein for DNA replication in E. coli. There are two putative DnaA-binding sites within the extended promoter region of polA. In this work we studied the influence of altered levels of DnaA protein on polA expression. We found that DnaA overproduction increases polA expression in stationary-phase cultures. The stimulation effect was independent of rpoS, which encodes the sigma factor for stationary-phase-inducible genes. However, it was modulated by ppGpp. Comparative S1 analyses revealed that the induction was based on transcriptional stimulation. Footprint-ing experiments demonstrated that DnaA binds only to the proximal DnaA box near the polA promoter. These results suggest an additional role for DnaA as transcriptional activator of polA at least under certain physiological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2961658.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Molecular characterization of the Bacillus anthracis main S-layer component: evidence that it is the major cell-associated antigen (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Bacillus anthracis, the aetiological agent of anthrax, is a Gram-positive spore-forming bacterium. The cell wall of vegetative cells of B. anthracis is surrounded by an S-layer. An array remained when sap, a gene described as encoding an S-layer component, was deleted. The remaining S-layer component, termed EA1, is chromosomally encoded. The gene encoding EA1 (eag) was obtained on two overlapping fragments in Escherichia coli and shown to be contiguous to the sap gene. The EA1 amino acid sequence, deduced from the eag nucleotide sequence, shows classical S-layer protein features (no cysteine, only 0.1% methionine, 10% lysine, and a weakly acidic pi). Similar to Sap and other Gram-positive surface proteins, EA1 has three 'S-layer-homology’motifs immediately downstream from a signal peptide. Single- and double-disrupted mutants were constructed. EA1 and Sap were co-localized at the cell surface of the wild-type bacilli. However, EA1 was more tightly bound than Sap to the bacteria. Electron microscopy studies and in vivo experiments with the constructed mutants showed that EA1 constitutes the main lattice of the B. anthracis S-layer, and is the major cell-associated antigen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2941659.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Random shuttle mutagenesis: gonococcal mutants deficient in pilin antigenic variation (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Shuttle mutagenesis has been adapted to randomly mutate the genome of Neisseria gonorrhoeae (gono-coccus; Gc). A size-restricted plasmid library of Gc strain FA1090 was mutated with the mini-transposon mTnEGNS. Randomness was tested by checking for transposon insertion bias between vector and insert DNA, Gc transformation efficiency of individual mutated clones, and representation of unique clones before and after Gc transformation with a mutated pool of DNA. Mutants created by random shuttle mutagenesis were screened, using a colony-based polymerase chain reaction assay, for the ability to undergo pilin antigenic variation. Out of 8064 mutants screened, 22 unique transposon insertion mutants were found to be antigenic variation deficient (Avd). The Avd mutants were separated into five types according to recombination defect-associated phenotypes, including colony growth, natural DNA transformation competence, and repair of DNA damage caused by ultraviolet radiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2971660.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Replication of minichromosomes in a host in which chromosome replication is random (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Minichromosomes are plasmids with the origin of chromosome replication, oriC, as their only origin of replication. In Escherichia coli, minichromosomes are compatible with the chromosome and replicate in a cell-cycle-specific manner at the same time as oriC located on the chromosome initiates replication. In int strains, oriC has been inactivated and replaced by a plasmid origin. Because plasmids control their own replication, chromosome replication is uncoupled from the normal cell-cycle control and is random with respect to the cell cycle in the int strains. We have used an intP1 strain to address the question of whether minicromosome replication is coupled to the replication of the chromosome or is governed by cell-cycle-specific signals. Minichromosome replication was analysed by density-shift experiments and found not to be random in the randomly replicating intP1 host. This suggests that the cell-cycle-specific control functions of oriC replication are operating also in the intP1 strain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2981663.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Maltose-binding protein interacts simultaneously and asymmetrically with both subunits of the Tar chemoreceptor (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Tar chemotactic signal transducer of Escherichia coli mediates attractant responses to L-aspartate and to maltose. Aspartate binds across the subunit interface of the periplasmic receptor domain of a Tar homodimer. Maltose, in contrast, first binds to the periplasmic maltose-binding protein (MBP), which in its ligand-stabilized closed form then interacts with Tar. Intragenic complementation was used to determine the MBP-binding site on the Tar dimer. Mutations causing certain substitutions at residues Tyr-143, Asn-145, Gly-147, Tyr-149, and Phe-150 of Tar lead to severe defects in maltose chemotaxis, as do certain mutations affecting residues Arg-73, Met-76, Asp-77, and Ser-83. These two sets of mutations defined two complementation groups when the defective proteins were co-expressed at equal levels from compatible plasmids. We conclude that MBP contacts both subunits of the Tar dimer simultaneously and asymmetrically. Mutations affecting Met-75 could not be complemented, suggesting that this residue is important for association of MBP with each subunit of the Tar dimer. When the residues involved in interaction with MBP were mapped onto the crystal structure of the Tar periplasmic domain, they localized to a groove at the membrane-distal apex of the domain and also extended onto one shoulder of the apical region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3001661.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Gzf3p, a fourth GATA factor involved in nitrogen-regulated transcription in Saccharomyces cerevisiae (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In Saccharomyces cerevisiae, two positive transcription factors of the GATA family, Gln3p and NiMp/ Gatlp, upregulate the expression of multiple nitrogen pathway genes via upstream 5-GATA-3′ sequences. Another GATA factor, Uga43p/Da180p, downregulates to varying degrees the expression of some nitrogen-regulated genes. Here, we report the functional analysis of a fourth GATA factor, Gzf 3p/Ni12p, whose gene was discovered by systematic sequencing of chromosome X. The Gzf3 protein most closely resembles Uga43p. Similar to Uga43p, Gzf3p has the properties of a negative GATA factor. While Uga43p is active specifically under nitrogen-derepression conditions, Gzf 3p exerts its negative regulatory function specifically on preferred nitrogen sources: it is involved in nitrogen repression of NiMp-dependent transcription. At least one positive GATA factor is required for the UGA43 and GZF3 genes to be expressed. The Uga43p factor negatively regulates GZF3 expression and vice versa. In addition, both Uga43p and Gzf3p moderately regulate expression of their own genes. These two proteins seem to be parts of a complex network of GATA factors which probably play a determining role in nitrogen-regulated transcription.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3021665.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Different structures of selected and unselected araB-lacZ fusions (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Formation of araB-lacZ coding-sequence fusions is a key adaptive mutation system. Eighty-four independent araB-lacZ fusions were sequenced. All fusions carried rearranged MuR linker sequences between the araB and lacZ domains indicating that they arose from the standard intermediate of the well-characterized Mu DNA rearrangement process, the strand transfer complex (STC). Five non-standard araB-lacZ fusions isolated after indirect sib selection had novel structures containing back-to-back inverted MuR linkers. The observation that different isolation procedures gave rise to standard and non-standard fusions indicates that cellular physiology can influence late steps in the multi-step biochemical sequence leading to araB-lacZ fusions. Each araB-lacZ fusion contained two novel DNA junctions. The MuR-lacZ junctions showed‘hot-spotting’according to established rules for Mu target selection. The araB-MuR and MuR-MuR junctions all involved exchanges at regions of short sequence homology. More extensive homology between MuR and araB sequences indicates potential STC isomerization into a resolvable four-way structure analogous to a Holliday junction. These results highlight the molecular complexity of araB-lacZ fusion formation, which may be thought of as a multi-step cell biological process rather than a unitary biochemical reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3031666.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    A novel regulatory system required for pathogenicity of Xanthomonas campestris is mediated by a small diffusible signal molecule (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Mutations in the seven clustered rpf genes cause downregulated synthesis of extracellular enzymes and reduced virulence of Xanthomonas campestris pathovar campestris (Xcc). The phenotype of mutants in one of the genes, rpfF, can be restored by a diffusible extracellular factor (DSF) produced by all Xcc strains tested, apart from rpfF and rpfB mutants. DSF accumulates in early stationary phase (when synthesis of enzymes is maximal), but levels decline subsequently. Addition of DSF to exponentially-growing wild-type bacteria does not cause precocious enzyme synthesis. rpfB and rpfF are expressed throughout growth, but the rate increases in early stationary phase. RpfB is predicted to be a long-chain fatty acyl CoA ligase, and RpfF shows some relatedness to enoyl CoA hydratases. The properties of DSF suggest that it may be a fatty-acid derivative, and certain lipid preparations possess DSF activity at higher concentrations. These include lipid extracts and acid-hydrolysed lipopolysaccharide and lipid A from Xcc, and purified dodecanoic and hydroxydodecanoic acid. DSF production is confined to certain xanthomonads. We propose a model for the DSF system, which represents a novel mechanism for regulating virulence factor synthesis in response to physiological or environmental changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3721736.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    A C-terminal di-leucine motif and nearby sequences are required for NH4+-induced inactivation and degradation of the general amino acid permease, Gap1p, of Saccharomyces cerevisiae (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The general amino acid permease, Gap1, of Saccharomyces cerevisiae is very active in cells grown on proline as the sole nitrogen source. Adding NH4+ to the medium triggers inactivation and degradation of the permease via a regulatory process involving Npi1p/Rsp5p, a ubiquitin–protein ligase. In this study, we describe several mutations affecting the C-terminal region of Gap1p that render the permease resistant to NH4+-induced inactivation. An in vivo isolated mutation (gap1pgr ) causes a single Glu→Lys substitution in an amino acid context similar to the DXKSS sequence involved in ubiquitination and endocytosis of the yeast α-factor receptor, Ste2p. Another replacement, substitution of two alanines for a di-leucine motif, likewise protects the Gap1 permease against NH4+-induced inactivation. In mammalian cells, such a motif is involved in the internalization of several cell-surface proteins. These data provide the first indication that a di-leucine motif influences the function of a plasma membrane protein in yeast. Mutagenesis of a putative phosphorylation site upstream from the di-leucine motif altered neither the activity nor the regulation of the permease. In contrast, deletion of the last eleven amino acids of Gap1p, a region conserved in other amino acid permeases, conferred resistance to NH4+ inactivation. Although the C-terminal region of Gap1p plays an important role in nitrogen control of activity, it was not sufficient to confer this regulation to two NH4+-insensitive permeases, namely the arginine (Can1p) and uracil (Fur4p) permeases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3771735.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    HlyX, the FNR homologue of Actinobacillus pleuropneumoniae, is a [4Fe–4S]-containing oxygen-responsive transcription regulator that anaerobically activates FNR-dependent Class I promoters via an enhanced AR1 contact (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The hlyX gene of the pig pathogen Actinobacillus pleuropneumoniae encodes HlyX, a homologue of FNR, the anaerobic transcription regulator of Escherichia coli. The hlyX gene complements the anaerobic respiratory deficiencies of E. coli fnr mutants but also induces the expression of an otherwise latent haemolysin. Therefore, FNR and HlyX have distinct but overlapping regulons. The hlyX gene has been overexpressed as a gst ::hlyX fusion and the HlyX protein purified. Similar to FNR, HlyX can acquire a [4Fe–4S] cluster, which promotes binding to the FNR box (Kd of 20–30 nM) under anaerobic conditions. Expression of hlyX in E. coli induced the anaerobic production of at least five polypeptides, including the yfiD gene product, which were not induced by fnr. Analysis of the yfiD promoter region revealed the presence of two FNR boxes situated at −61.5 and −114.5. Consistent with this observation, expression from the semi-synthetic Class I promoter FF+20pmelR was efficiently activated by HlyX but not by FNR. The weaker level of FNR-mediated activation of Class I promoters suggests that there is a poorer activating contact (activating region 1 (AR1) equivalent) between FNR and RNA polymerase at these promoters and that HlyX possesses an additional or improved AR1. The AR1 of HlyX is partially characterized by a surface-exposed region around amino acid A187, which confers the altered specificity and provides an explanation for the existence of distinct but overlapping HlyX and FNR regulons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3801737.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Use of time-lapse microscopy to visualize rapid movement of the replication origin region of the chromosome during the cell cycle in Bacillus subtilis (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We describe the use of time-lapse fluorescence microscopy to visualize the movement of the DNA replication origin and terminus regions on the Bacillus subtilis chromosome during the course of the cell cycle. The origin and terminus regions were tagged with a cassette of tandem lac operator repeats and visualized through the use of a fusion of the green fluorescent protein to the LacI repressor. We have discovered that origin regions abruptly move apart towards the cell poles during a brief interval of the cell cycle. This movement was also seen in the absence of cell wall growth and in the absence of the product of the parB homologue spo0J. The origin regions moved apart an average distance of 1.4 μm in an 11 min period of abrupt movement, representing an average velocity of 0.17 μm min−1. and reaching a maximum velocity of greater than 0.27 μm min−1. The terminus region also exhibited a striking pattern of movement but not as far or a rapid as the origin region. These results provide evidence for a mitotic-like motor that is responsible for segregation of the origin regions of the chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00808.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    PRD — a protein domain involved in PTS-dependent induction and carbon catabolite repression of catabolic operons in bacteria (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Several operon-specific transcriptional regulators, including antiterminators and activators, contain a duplicated conserved domain, the PTS regulation domain (PRD). These duplicated domains modify the activity of the transcriptional regulators both positively and negatively. PRD-containing regulators are very common in Gram-positive bacteria. In contrast, antiterminators controlling β-glucoside utilization are the only functionally characterized members of this family from Gram-negative bacteria. PRD-containing regulators are controlled by PTS-dependent phosphorylation with different consequences: (i) In the absence of inducer, the phosphorylated EIIB component of the sugar permease donates its phosphate to a PRD, thereby inactivating the regulator. In the presence of the substrate, the regulator is dephosphorylated, and the phosphate is transferred to the sugar, resulting in induction of the operon. (ii) In Gram-positive bacteria, a novel mechanism of carbon catabolite repression mediated by PRD-containing regulators has been demonstrated. In the absence of PTS substrates, the HPr protein is phosphorylated by enzyme I at His-15. This form of HPr can, in turn, phosphorylate PRD-containing regulators and stimulate their activity. In the presence of rapidly metabolizable carbon sources, ATP-dependent phosphorylation of HPr at Ser-46 by HPr kinase inhibits phosphorylation by enzyme I, and PRD-containing regulators cannot, therefore, be stimulated and are inactive. All regulators of this family contain two copies of PRD, which are functionally specialized in either induction or catabolite repression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00839.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    The telomeres of Streptomyces chromosomes contain conserved palindromic sequences with potential to form complex secondary structures (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The chromosomes of the Gram-positive soil bacteria Streptomyces are linear DNA molecules, usually of about 8 Mb, containing a centrally located origin of replication and covalently bound terminal proteins (which are presumably involved in the completion of replication of the telomeres). The ends of the chromosomes contain inverted repeats of variable lengths. The terminal segments of five Streptomyces chromosomes and plasmids were cloned and sequenced. The sequences showed a high degree of conservation in the first 166–168 bp. Beyond the terminal homology, the sequences diverged and did not generally cross-hybridize. The homologous regions contained seven palindromes with a few nucleotide differences. Many of these differences occur in complementary pairs, such that the palindromicity is preserved. Energy-optimized modelling predicted that the 3′ strand of the terminal palindromes can form extensive hairpin structures that are similar to the 3′ ends of autonomous parvovirus genomes. Most of the putative hairpins have a GCGCAGC sequence at the loop, with the potential to form a stable single C-residue loop closed by a sheared G:A pairing. The similarity between the terminal structures of the Streptomyces replicons and the autonomous parvoviral genomes suggests that they may share some structural and/or replication features.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00856.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    In vivo relations between pAMβ1-encoded type I topoisomerase and plasmid replication (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A number of large extrachromosomal elements encode prokaryotic type I topoisomerases of unknown functions. Here, we analysed the topoisomerase Topβ encoded by the Gram-positive broad-host-range plasmid pAMβ1. We show that this enzyme possesses the DNA relaxation activity of type I topoisomerases. Interestingly, it is active only on plasmids that use DNA polymerase I to initiate replication, such as pAMβ1, and depends on the activity of this polymerase. This is the first example, to our knowledge, of prokaryotic type I topoisomerase that is specific for a given type of replicon. During pAMβ1 replication in Bacillus subtilis cells, Topβ promotes premature arrest of DNA polymerase I, ≈190 bp downstream of the replication initiation point. We propose that Topβ acts on the early replication intermediates of pAMβ1, which contain D-loops formed by DNA polymerase I-mediated strand displacement. The possible role of the resulting DNA Pol I arrest in plasmid replication is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00862.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    Prophage genes in Salmonella: response to Ali and Pallen (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00863.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Phage-encoded genes and Salmonella virulence (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00864.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Natural competence for DNA transformation in Helicobacter pylori : identification and genetic characterization of the comB locus (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Gram-negative bacterial pathogen Helicobacter pylori, an important aetiological agent of gastroduodenal disease in humans, belongs to a group of bacterial species displaying competence for genetic transformation. Here, we describe the comB gene locus of H. pylori involved in DNA transformation competence. It consists of a cluster of four tandemly arranged genes with partially overlapping open reading frames, orf2, comB1, comB2 and comB3, constituting a single transcriptional unit. Orf2 encodes a 37-amino-acid peptide carrying a signal sequence, whereas comB1, comB2 and comB3 produce 29 kDa, 38 kDa and 42 kDa proteins, respectively, as demonstrated by immunoblotting with specific antisera. For Orf2 and ComB1, no homologous proteins were identified in the database. For ComB3, the best homologies were found with TraS/TraB from the Pseudomonas aeruginosa conjugative plasmid RP1 and TrbI of plasmid RP4, VirB10 from the Ti plasmid of Agrobacterium tumefaciens and PtlG, a protein involved in secretion of pertussis toxin of Bordetella pertussis. Defined transposon knock-out mutants in individual comB genes resulted in transformation-defective phenotypes ranging from a 90% reduction to a complete loss of the natural transformation efficiency. The comB2 and comB3 genes show homology to HP0528 and HP0527, respectively, located on the cagII pathogenicity island of H. pylori strain 26695.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00879.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Tandem genes of Chlamydia psittaci that encode proteins localized to the inclusion membrane (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Chlamydiae are obligate intracellular bacteria that replicate within a non-acidified vacuole, termed an inclusion. To identify chlamydial proteins that are unique to the intracellular phase of the life cycle, a lambda expression library of Chlamydia psittaci DNA was differentially screened with convalescent antisera from infected guinea pigs and antisera directed at formalin-fixed purified chlamydial elementary bodies (EBs). One library clone was identified that harboured two open reading frames (ORFs) with coding potential for similar-sized proteins of ≈20 kDa. These proteins were subsequently termed IncB and IncC. Sequencing of the cloned insert revealed a strong Escherichia coli-like promoter sequence immediately upstream of incB and a 36 nt intergenic region between the ORFs. Sequence analysis of the region upstream of incB and incC revealed two ORFs that had strong homologies to an amino acid transporter and a sodium-dependent transporter. Immunoblotting with antisera directed at IncB or IncC demonstrated that these proteins are present in C. psittaci-infected HeLa cells but are absent or below the level of detection in purified EBs. Reverse transcriptase-polymerase chain reactions provided evidence that incB and incC are transcribed in an operon. Immunofluorescence microscopy demonstrated that IncB and IncC are each localized to the inclusion membrane of infected cells. No primary sequence similarity is evident between IncA, IncB or IncC, but each contains a large hydrophobic domain of similar size and character as in IncA. Analysis of the recently completed C. trachomatis serovar D genome database has revealed C. trachomatis ORFs encoding homologues to incB and incC, indicating that these genes are conserved among the chlamydiae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00867.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    Decorin-binding adhesins from Borrelia burgdorferi (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Lyme disease is a tick-transmitted infection caused by the spirochete Borrelia burgdorferi. Ticks deposit B. burgdorferi into the dermis of the host, where they eventually become associated with collagen fibres. We demonstrated previously that B. burgdorferi is unable to bind collagen, but can bind the collagen-associated proteoglycan decorin and expresses decorin-binding proteins (Dbps). We have now cloned and sequenced two genes encoding the proteins, DbpA and DbpB, which have a similar structure, as revealed by circular dichroism (CD) spectroscopy of recombinant proteins. Competition experiments revealed a difference in binding specificity between DbpA and DbpB. Western blot analysis of proteinase K-treated intact B. burgdorferi and transmission electron microscopy studies using antibodies raised against recombinant Dbps demonstrated that these proteins are surface exposed. DbpA effectively inhibits the attachment of B. burgdorferi to a decorin substrate, whereas DbpB had a marginal effect, suggesting a difference in substrate specificity between the two Dbps. Polystyrene beads coated with DbpA adhered to a decorin-containing extracellular matrix produced by cultured skin fibroblasts, whereas beads coated with OspC did not. Taken together, these data suggest that Dbps are adhesins of the MSCRAMM (microbial surface component-recognizing adhesive matrix molecule) family, which mediate B. burgdorferi attachment to the extracellular matrix of the host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01103.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    The S box regulon: a new global transcription termination control system for methionine and cysteine biosynthesis genes in Gram-positive bacteria (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The molecular mechanisms for regulation of the genes involved in the biosynthesis of methionine and cysteine are poorly characterized in Bacillus subtilis. Analyses of the recently completed B. subtilis genome revealed 11 copies of a highly conserved motif. In all cases, this motif was located in the leader region of putative transcriptional units, upstream of coding sequences that included genes involved in methionine or cysteine biosynthesis. Additional copies were identified in Clostridium acetobutylicum and Staphylococcus aureus, indicating conservation in other Gram-positive genera. The motif includes an element resembling an intrinsic transcriptional terminator, suggesting that regulation might be controlled at the level of premature termination of transcription. The 5′ portion of all of the leaders could fold into a conserved complex structure. Analysis of the yitJ gene, which is homologous to Escherichia coli metH and metF, revealed that expression was induced by starvation for methionine and that induction was independent of the promoter and dependent on the leader region terminator. Mutation of conserved primary sequence and structural elements supported a model in which the 5′ portion of the leader forms an anti-antiterminator structure, which sequesters sequences required for the formation of an antiterminator, which, in turn, sequesters sequences required for the formation of the terminator; the anti-antiterminator is postulated to be stabilized by the binding of some unknown factor when methionine is available. This set of genes is proposed to form a new regulon controlled by a global termination control system, which we designate the S box system, as most of the genes are involved in sulphur metabolism and biosynthesis of methionine and cysteine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01105.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Adaptation of Haemophilus influenzae to acquired and innate humoral immunity based on phase variation of lipopolysaccharide (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Phase variation in colony morphology has been associated with the pathogenesis of infection caused by Haemophilus influenzae. This study shows that differences in colony opacity in non-typeable H. influenzae (NTHi) strain H233 involve phase changes in the lipopolysaccharide (LPS) and depend on the expression of lic1 and lic2, which contain translational switches based on intragenic tandem repeats of 5′-CAAT-3′. Genetic analysis showed that opaque organisms have an out-of-frame number of repeats in both lic1, required for the expression of phosphorylcholine (ChoP), and lic2, a putative galactosyl transferase that adds the terminal galactose on Galα1-4Gal. Defined variants in these loci were used to examine the contribution of individual LPS structures to resistance to serum bactericidal activity mediated by antibody and C-reactive protein (CRP). The addition of ChoP by lic1 was the only factor in serum killing involving CRP and complement. The terminal galactose moiety, in contrast, conferred resistance to killing by naturally acquired antibody and complement present in human serum. As Galα1-4Gal is also found on human glycolipids, it appears that decoration of the cell surface with this host-like antigen blocks antibody-mediated serum bactericidal activity. Genetic analysis of NTHi within the human respiratory tract demonstrated that Galα1-4Gal may not be expressed during carriage but may be advantageous for the organism in inflammatory states such as pneumonia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01108.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Transcriptional activation of the glycolytic las operon and catabolite repression of the gal operon in Lactococcus lactis are mediated by the catabolite control protein CcpA (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Lactococcus lactis ccpA gene, encoding the global regulatory protein CcpA, was identified and characterized. Northern blot and primer extension analyses showed that the L. lactis ccpA gene is constitutively transcribed from a promoter that does not contain a cre sequence. Inactivation of the ccpA gene resulted in a twofold reduction in the growth rate compared with the wild type on glucose, sucrose and fructose, while growth on galactose was almost completely abolished. The observed growth defects could be complemented by the expression of either the L. lactis or the Bacillus subtilis ccpA gene. The disruption of the ccpA gene reduced the catabolite repression of the gal operon, which contains a cre site at the transcription start site and encodes enzymes involved in galactose catabolism. In contrast, CcpA activates the transcription of the cre-containing promoter of the las operon, encoding the glycolytic enzymes phosphofructokinase, pyruvate kinase and L-lactate dehydrogenase, because its transcription level was fourfold reduced in the ccpA mutant strain compared with the wild-type strain. The lower activities of pyruvate kinase and L-lactate dehydrogenase in the ccpA mutant strain resulted in the production of metabolites characteristic of a mixed-acid fermentation, whereas the fermentation pattern of the wild-type strain was essentially homolactic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01111.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    Increased nuclear traffic chaos in hyphae of Aspergillus nidulans: molecular characterization of apsB and in vivo observation of nuclear behaviour (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Filamentous fungi are model microorganisms for studying nuclear migration in eukaryotic cells. Two genes, apsA and apsB (= anucleate primary sterigmata), were identified in Aspergillus nidulans that affect nuclear distribution in hyphae and specifically block conidiophore development at the metula stage when mutant. Here we describe the cloning, sequencing and molecular analysis of apsB. The gene encodes a 121 kDa coiled-coil, hydrophilic protein that was localized in the cytoplasm. No protein–protein interaction was detected between ApsB and ApsA, a membrane-associated, previously identified protein. An apsB null mutant was characterized by video epifluorescence microscopy using strains that express green fluorescent protein (GFP) in nuclei. With this novel approach, we have discovered a new mutant phenotype and have found that nuclei display an increased chaotic movement in older hyphal compartments that results in clustering and an uneven distribution of these organelles. These results suggest a regulatory role of ApsB in nuclear migration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01115.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    In vitro and in vivo expression studies of yopE from Yersinia enterocolitica using the gfp reporter gene (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Yersinia outer protein YopE belongs to the translocated effector proteins of pathogenic yersiniae. We constructed various truncated yopE genes fused to gfp (encoding the green fluorescent protein) to study yopE gene expression and YopE–GFP translocation of Y. enterocolitica in cell culture and mouse infection models. The hybrid gene fusions were co-expressed in Y. enterocolitica (i) on a low-copy plasmid in the presence of the virulence plasmid pYV08 (in trans configuration) and (ii) after co-integration by homologous recombination of a yopE–gfp-carrying suicide plasmid into pYV08 (co-integrate configuration). After 30 min of infection of HEp-2 cell monolayers, extracellularly located yersiniae began to emit green fluorescence after excitation. In contrast, internalized bacteria were weakly fluorescent. Translocation of YopE–GFP into HEp-2 cells by attached yersiniae was visualized by optical sectioning of fluorescent HEp-2 cells using confocal laser scanning microscopy and was confirmed by immunoprecipitation of cytosolic YopE–GFP from selectively solubilized HEp-2 cells. The co-translocation of other Yops was not significantly impaired by YopE–GFP as shown by YopH/YopE-mediated suppression of the oxidative burst of infected neutrophils. The time course of yopE–gfp expression (in trans as well as in the co-integrate configuration) in the HEp-2 cell infection model as well as after in vitro induction was studied using a highly sensitive CCD camera and a flow cytometer. Similar results were obtained with a YopE–LUC (firefly luciferase) protein fusion as reporter. After intraperitoneal, intravenous and orogastrical infection of Balb/c mice with the recombinant yersiniae strains, green fluorescing bacteria could be visualized microscopically in the peritoneum, the spleen, the liver and in the Peyer's patches. However, only weakly fluorescent yersiniae were observed in the intestinal lumen. These results were quantified by flow cytometric measurements. The application of gfp as a reporter gene turned out to be promising for the study of protein translocation by protein type III secretion systems and differential virulence gene expression in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01128.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    The fats of Escherichia coli during infancy and old age: regulation by global regulators, alarmones and lipid intermediates (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The fluidity and phase state of bacterial lipid bilayers commonly change in response to ambient environmental conditions to maintain the critical functions of the envelope as a semipermeable and selective boundary. A special, and intricate, set of alterations in membrane lipid metabolism is elicited by conditions causing growth arrest. Under such conditions, specific alterations in the membrane lipid–fatty acid composition are required for survival of the cell and, concurrently, the membrane lipids are suggested to serve as endogenous reserves providing carbon/energy for maintenance requirements. It appears that the global regulator FadR is required for both of these activities to be performed properly and that the FadR regulon is interconnected to the universal stress response of Escherichia coli. FadR, in conjuction with long-chain fatty acyl-CoA, long-chain acyl-ACP, ppGpp and cAMP, are key players in regulating the activities of enzymes and expression of genes involved in fatty acid and phospholipid metabolism in dividing and ageing E. coli cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00645.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Bacteriophage T7 mRNA is polyadenylated (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: To determine whether the RNA of bacterial viruses is polyadenylated like bacterial mRNAs, pulse-labelled as well as the steady-state population of bacteriophage T7-specific transcripts were examined for the presence of poly(A) tracts by binding to oligo(dT) cellulose followed by hybridization with specific gene probes. Representatives of all classes of bacteriophage-specific mRNA — early, middle and late — were found to be polyadenylated. This conclusion was confirmed by screening the products of oligo(dT)-dependent cDNA synthesis. A cDNA library was prepared from RNA synthesized after bacteriophage T7 infection and the sequence of bacteriophage-specific clones was determined to define the sites of polyadenylation. About half of the clones were polyadenylated near the end of a protein-coding region, one of them at the site of post-transcriptional processing by RNase III. Other clones were polyadenylated within protein-coding regions. These observations suggest that polyadenylation occurs after the nucleolytic processing of primary transcripts and in some cases also after mRNA degradation has already begun.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00649.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Identification of a gene essential for O-acetylation of the Staphylococcus aureus type 5 capsular polysaccharide (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Staphylococcus aureus serotype 5 capsular polysaccharide (CP5) has a trisaccharide repeating unit of (→ 4)-3-O-Ac-β-D-ManNAcAp-(1 → 4)-α-L-FucNAcp-(1 → 3)-β-D-FucNAcp-(1→). Tn918 mutagenesis of strain Reynolds yielded a mutant that produced wild-type levels of O-deacetylated CP5. The site and orientation of the single transposon insertion in mutant JL232 were determined by analysis of Southern blots and amplification of DNA flanking the transposon. DNA sequencing revealed that Tn918 was inserted within an open reading frame of 627 bp. The predicted amino acid sequence encodes a protein of approximately 26 kDa with homology to members of the NodL-LacA-CysE family of bacterial acetyltransferases. Southern blot analysis showed that genes similar to cap5H were present only in strains of S. aureus belonging to capsular serotypes 2, 4 and 5. In an in vitro assay, the parental strain was more resistant to opsonophagocytic killing than the mutant strain. In a mouse model of staphylococcal infection, the parental strain was able to seed the bloodstream from the peritoneal cavity and colonize the kidneys more efficiently than the O-deacetylated mutant. When cap5H was provided to the mutant in trans, it fully restored CP5 O-acetylation. The virulence of the complemented mutant strain closely approximated that of the parental strain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00646.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    The secretion apparatus of Pseudomonas aeruginosa: identification of a fifth pseudopilin, XcpX (GspK family) (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The xcp gene products in Pseudomonas aeruginosa are required for the secretion of proteins across the outer membrane. Four of the Xcp proteins, XcpT, U, V and W, present sequence homology to the subunits of type IV pili at their N-termini, and they were therefore designated pseudopilins. In this study, we characterized the xcpX gene product, a bitopic cytoplasmic membrane protein. Remarkably, amino acid sequence comparisons also suggested that the XcpX protein resembles the pilins and pseudopilins at the N-terminus. We show that XcpX could be processed by the prepilin peptidase, PilD/XcpA, and that the highly conserved glycine residue preceding the hydrophobic segment could not be mutated without loss of the XcpX function. We, therefore, classified XcpX (GspK) as the fifth pseudopilin of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00653.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    DNA-binding characteristics of the Escherichia coli CytR regulator: a relaxed spacing requirement between operator half-sites is provided by a flexible, unstructured interdomain linker (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Escherichia coli CytR regulator belongs to the LacI family of sequence-specific DNA-binding proteins and prevents CRP-mediated transcription in the CytR regulon. Unlike the other members of this protein family, CytR binds with only modest affinity to its operators and transcription repression thus relies on the formation of nucleoprotein complexes with the cAMP–CRP complex. Moreover, CytR exhibits a rotational and translational flexibility in operator binding that is unprecedented in the LacI family. In this report we examined the effect of changing the spacing between CytR half-operators on CytR regulation in vivo and on CytR binding in vitro. Maximum repression was seen with the short spacing variants: repression peaks when the half-operators lie on the same face of the DNA helix. Repression was retained for most spacing variants with centre separations of half-operators ≤ 3 helical turns. Our data confirm and extend the view that CytR is a highly flexible DNA binder that can adapt many different conformations for co-operative binding with CRP. Furthermore, limited proteolysis of radiolabelled CytR protein showed that the interdomain linker connecting the DNA binding domains and the core part of CytR does not become structured upon DNA binding. We conclude that CytR does not use hinge α-helices for minor groove recognition. Rather, CytR possesses a highly flexible interdomain linker that allows it to form complexes with CRP at promoters with quite different architecture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00655.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Haemoglobin receptor protein is intragenically encoded by the cysteine proteinase-encoding genes and the haemagglutinin-encoding gene of Porphyromonas gingivalis (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The obligately anaerobic bacterium Porphyromonas gingivalis produces characteristic black-pigmented colonies on blood agar. It is thought that the black pigmentation is caused by haem accumulation and is related to virulence of the microorganism. P. gingivalis cells expressed a prominent 19 kDa protein when grown on blood agar plates. Analysis of its N-terminal amino acid sequence indicated that the 19 kDa protein was encoded by an internal region (HGP15 domain) of an arginine-specific cysteine proteinase (Arg-gingipain, RGP)-encoding gene (rgp1) and was also present in genes for lysine-specific cysteine proteinases (prtP and kgp) and a haemagglutinin (hagA) of P. gingivalis. The HGP15 domain protein was purified from an HGP15-overproducing Escherichia coli and was found to have the ability to bind to haemoglobin in a pH-dependent manner. The anti-HGP15 antiserum reacted with the 19 kDa haemoglobin-binding protein in the envelope of P. gingivalis. P. gingivalis wild-type strain showed pH-dependent haemoglobin adsorption, whereas its non-pigmented mutants that produced no HGP15-related proteins showed deficiency in haemoglobin adsorption. These results strongly indicate a close relationship among HGP15 production, haemoglobin adsorption and haem accumulation of P. gingivalis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00656.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a putative multidrug resistance pump from Vibrio cholerae (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Multidrug-resistant strains of Vibrio cholerae (the causative agent of the diarrhoeal disease cholera) have recently been described. In an attempt to identify a homologue of the Escherichia coli TolC in V. cholerae, we isolated a DNA fragment (pVC) that enabled an E. coli tolC mutant to grow in the presence of 0.05% deoxycholate (DOC). However, other TolC defects were not complemented. Nucleotide sequence analysis of this fragment revealed the presence of two open reading frames (ORF1 and ORF2) separated by 9 bp and encoding 42.4 and 55.8 kDa proteins respectively. The translational products of these two ORFs correlated closely with the molecular weights of the predicted proteins. The deduced amino acid sequences of ORF1 and ORF2 showed a high degree of similarity with conserved regions of the E. coli efflux pump proteins, EmrA and EmrB. The presence of pVC2 within the E. coli efflux pump mutants defective in either the emrAB or the acrAB genes provided the mutants with resistance against several antibiotics. A V. cholerae isogenic mutant defective in ORF2 was constructed by gene replacement. Characterization of this mutant has shown it to be more sensitive to CCCP, PMA, PCP, nalidixic acid and DOC than the parent strain. These results suggest that ORF1 and ORF2 constitute an operon encoding two components of a putative multidrug resistance pump in V. cholerae. In addition, the presence of both structural and functional similarities between VceAB and EmrAB suggests that VceAB is a homologue of EmrAB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00657.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    Competence-specific induction of recA is required for full recombination proficiency during transformation in Streptococcus pneumoniae (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Transcriptional activation of the recA gene of Streptococcus pneumoniae was previously shown to occur at competence. A 5.7 kb recA-specific transcript that contained at least two additional genes, cinA and dinF, was identified. We now report the complete characterization of the recA operon and investigation of the role of the competence-specific induction of recA. The 5.7 kb competence-specific recA transcript is shown to include lytA, which encodes the pneumococcal autolysin, a protein previously shown to contribute to virulence of S. pneumoniae. Uncoupling (denoted Ind−) of recA and/or the downstream genes was achieved through the placement of transcription terminators within the operon, either upstream or downstream of recA. Prevention of the competence-specific induction of recA severely affected spontaneous transformation. Transformation efficiencies of recA+ (Ind−) and of wild-type cells were compared under various conditions and with different donor DNA. Chromosomal transformation was reduced 17- (chromosomal donor) to 45-fold (recombinant plasmid donor), depending on the donor DNA, and plasmid establishment was reduced 129-fold. Measurement of uptake of radioactively labelled donor DNA in transformed cells in parallel with scoring for transformants (chromosomal donor) revealed normal uptake, but a 21-fold reduction in recombination in a recA+ (Ind−) strain, indicating that the transformation defect was primarily in recombination. Strikingly enough, a much larger (460-fold) reduction in recombination was observed for the shortest homologous donor fragment used (878 nucleotides long). Possible interpretations of the observation that basal RecA appears unable to promote efficient recombination whatever the number and the length of donor fragments taken up are proposed. The role of recA induction is discussed in view of the potential contribution of transformation to genome plasticity in this pathogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00668.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Genetic evidence of separate repressor and activator activities of the XylR regulator of the TOL plasmid, pWWO, of Pseudomonas putida (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The XylR protein encoded by pWWO, the TOL (toluene biodegradation) plasmid of Pseudomonas putida, activates at a distance the transcription of Pu and Ps, which are the two σ54-dependent promoters of the plasmid, but it also downregulates its own σ70-promoter, Pr, which divergently overlaps the upstream activating sites of Ps. All regulatory elements that control Pr activity have been faithfully reproduced in Escherichia coli, and the basis of the autoregulation of XylR transcription has been examined by monitoring the activity in vivo of different combinations of mutant proteins and promoters in rpoN+ and rpoN- genetic backgrounds. By using PsIPr regions bearing deleted or offset binding sites for XylR and the σ54-containing RNA polymerase, we could show that formation of a nucleoprotein complex involving the polymerase bound to the divergent promoter Ps is not required for downregulation of Pr. Mutant XylR proteins, G268N and A311V (mutated within the NTP-binding region of XylR) or R453H (affected in multi-merization), which are unable to activate (-dependent transcription from Ps, were indistinguishable from the wild-type XylR in their ability to repress a reporter Pr-lacZ fusion. Autoregulation of XylR is therefore due exclusively to the binding of the protein to its target sites at the Pr promoter. This allows one to define sensu stricto XylR as a transcriptional repressor, independently of its activator role in other promoters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3091673.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Pathogenicity islands of virulent bacteria: structure, function and impact on microbial evolution (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Virulence genes of pathogenic bacteria, which code for toxins, adhesins, invasins or other virulence factors, may be located on transmissible genetic elements such as transposons, plasmids or bacteriophages. In addition, such genes may be part of particular regions on the bacterial chromosome, termed‘pathogenicity islands’(Pais). Pathogenicity islands are found in Gram-negative as well as in Gram-positive bacteria. They are present in the genome of pathogenic strains of a given species but absent or only rarely present in those of non-pathogenic variants of the same or related species. They comprise large DNA regions (up to 200 kb of DNA) and often carry more than one virulence gene, the G+C contents of which often differ from those of the remaining bacterial genome. In most cases, Pais are flanked by specific DNA sequences, such as direct repeats or insertion sequence (IS) elements. In addition, Pais of certain bacteria (e.g. uropathogenic Escherichia coli, Yersinia spp., Helicobacter pylori) have the tendency to delete with high frequencies or may undergo duplications and amplifications. Pais are often associated with tRNA loci, which may represent target sites for the chromosomal integration of these elements. Bacteriophage attachment sites and cryptic genes on Pais, which are homologous to phage integrase genes, plasmid origins of replication or IS elements, indicate that these particular genetic elements were previously able to spread among bacterial populations by horizontal gene transfer, a process known to contribute to microbial evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3101672.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Autoregulation of the Escherichia coli replication initiator protein, DnaA, is indirect (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The expression of dnaA is autoregulated, in that transcription of the gene increases when DnaA is inactivated (and initiation of replication prevented) and decreases when DnaA is supplied in excess. However, the inactivation of DnaA does not necessarily lead to increased DnaA production, as dnaA(7s; temperature sensitive) strains which are integratively suppressed by derivatives of the plasmid R1 do not show temperature-induced derepression. Several possible explanations for this unanticipated behaviour were considered and ruled out. We suggest here that the completion of a critical step in initiation may prevent dnaA derepression: although DnaA would be required to complete this step at oriC, DnaA(Ts) would be sufficient at the R1 origin. Autoregulation of dnaA has been attributed to the binding of DnaA at a consensus binding site in the dnaA promoter region. We show here, using reporter systems, that this DnaA-binding site is not required for the autoregu-latory response. We find, further, that replacement of the chromosomal dnaA gene with one containing a mutated binding site causes no demonstrable pheno-typic change: cells with the mutant gene show no disadvantage in competition with dnaA+ cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3121675.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    Double-glycine-type leader peptides direct secretion of bacteriocins by ABC transporters: colicin V secretion in Lactococcus lactis (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Many non-lantibiotic bacteriocins of lactic acid bacteria are produced as precursors which have N-terminal leader peptides that share similarities in amino acid sequence and contain a conserved processing site of two glycine residues in positions -1 and -2. A dedicated ATP-binding cassette (ABC) transporter is responsible for the proteolytic cleavage of the leader peptides and subsequent translocation of the bacteriocins across the cytoplasmic membrane. To investigate the role that these leader peptides play in the recognition of the precursor by the ABC transporters, the leader peptides of leucocin A, lactococcin A or colicin V were fused to divergicin A, a bacteriocin from Carnobacterlum divergens that is secreted via the cell's general secretion pathway. Production of divergicin was monitored when these fusion constructs were introduced into Leuconostoc gelidum, Lactococcus lactis and Escherichia coli, which carry the secretion apparatus for leucocin A, lactococcins A and B, and colicin V, respectively. The different leader peptides directed the production of divergicin in the homologous hosts. In some cases production of divergicin was also observed when the leader peptides were used in heterologous hosts. For ABC-transporter-dependent secretion in E. coli the outer membrane protein TolC was required. Using this strategy, colicin V was produced in L. lactis by fusing this bacteriocin behind the leader peptide of leucocin A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3111677.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    RNase E: still a wonderfully mysterious enzyme (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Ribonuclease E (RNase E), which is encoded by an essential Escherichia coli gene known variously as rne, ams, and hmp, was discovered initially as an rRNA-processing enzyme but is now known to have a general role in RNA decay. Multiple functions, including the ability to cleave RNA endonucleolyticaliy in AU-rich single-strand regions, RNA-binding capabilities, and the ability to interact with polynucleotide phosphorylase and other proteins implicated in the processing and degradation of RNA, are encoded by its 1061 amino acid residues. The presence of homologues and functional analogues of the rne gene in a variety of prokaryotic and eukaryotic species suggests that its functions have been highly conserved during evolution. While much has been learned in recent years about the structure and functions of RNase E, there is continuing mystery about possible additional activities and molecular interactions of this enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1997.tb02593.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    The nucleoside diphosphate kinase of Mycobacterium smegmatis: identification of proteins that modulate specificity of nucleoside triphosphate synthesis by the enzyme (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We report the purification and characterization of the enzyme nucleoside diphosphate kinase (Ndk) from Mycobacterium smegmatis. The N-terminus of the enzyme was blocked but an internal sequence showed approx. 70% homology with the same enzymes from Pseudomonas aeruginosa and Escherichia coli. Immobilization of the mycobacterial nucleoside diphosphate kinase on a Sepharose 4B matrix and passing the total cell extract through it revealed four proteins (P70, P65, P60, and P50, respectively) of Mr 70 kDa, 65 kDa, 60 kDa and 50 kDa that were retained by the column. While the proteins of Mr 70 kDa and 50 kDa modulated the activity of Ndk directing it towards GTP synthesis, the 60 kDa protein channelled the specificity of Ndk entirely towards CTP synthesis. The 65 kDa protein modulated the specificity of Ndk directing it entirely towards UTP synthesis. The specificity for such mycobacterial proteins towards NTP synthesis is retained when they are complexed with P. aeruginosa Ndk. We further demonstrate that the P70 protein is pyruvate kinase and that each of the four proteins forms a complex with Ndk and alters its substrate specificity. Given the ubiquitous nature of Ndk in the living cell and its role in maintaining correct ratios of intracellular nucleoside triphosphates, the implications of the occurrence of these complexes have been discussed in relation to the precursor pool for cell wall biosynthesis as well as RNA/DNA synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3491724.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    The C-terminal domain of the secretin PulD contains the binding site for its cognate chaperone, PulS, and confers PulS dependence on pIVf1 function (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Related outer membrane proteins, termed secretins, participate in the secretion of macromolecules across the outer membrane of many Gram-negative bacteria. In the pullulanase-secretion system, PulS, an outer membrane-associated lipoprotein, is required both for the integrity and the proper outer membrane localization of the PulD secretin. Here we show that the PulS-binding site is located within the C-terminal 65 residues of PulD. Addition of this domain to the filamentous phage secretin, pIV, or to the unrelated maltose-binding protein rendered both proteins dependent on PulS for stability. A chimeric protein composed of bacteriophage f1 pIV and the C-terminal domain of PulD required properly localized PulS to support phage assembly. An in vivo complex formed between the pIV-PulD65 chimera and PulS was detected by co-immunoprecipitation and by affinity chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3531727.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Structure of the DNA-binding domain of the OmpR family of response regulators (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3571723.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Structural basis for differential receptor binding of cholera and Escherichia coli heat-labile toxins: influence of heterologous amino acid substitutions in the cholera B-subunit (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The closely related B-subunits of cholera toxin (CTB) and Escherichia coli heat-labile enterotoxin (LTB) both bind strongly to GM1 ganglioside receptors but LTB can also bind to additional glycolipids and glycoproteins. A number of mutant CT B-subunits were generated by substituting CTB amino acids with those at the corresponding positions in LTB. These were used to investigate the influence of specific residues on receptor-binding specificity. A mutated CTB protein containing the first 25 residues of LTB in combination with LTB residues at positions 94 and 95, bound to the same extent as native LTB to both delipidized rabbit intestinal cell membranes, complex glycosphingolipids (polyglycosylceramides) and neolactotetraosylceramide, but not to non-GM1 intestinal glycosphingolipids. In contrast, when LTB amino acid substitutions in the 1–25 region were combined with those in the 75–83 region, a binding as strong as that of LTB to intestinal glycosphingolipids was observed. In addition, a mutant LTB with a single Gly-33→Asp substitution that completely lacked affinity for both GM1 and non-GM1 glycosphingolipids could still bind to receptors in the intestinal cell membranes and to polyglycosylceramides. We conclude that the extra, non-GM1 receptors for LTB consist of both sialylated and non-sialylated glycoconjugates, and that the binding to either class of receptors is influenced by different amino acid residues within the protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3541721.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    A quest for symbiosis-specific genes urges itself upon Rhizobium geneticists (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3581927.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Isolation and characterization of the mycobacterial phagosome: segregation from the endosomal/lysosomal pathway (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Mycobacteria have the ability to persist within host phagocytes, and their success as intracellular pathogens is thought to be related to the ability to modify their intracellular environment. After entry into phagocytes, mycobacteria-containing phagosomes acquire markers for the endosomal pathway, but do not fuse with lysosomes. The molecular machinery that is involved in the entry and survival of mycobacteria in host cells is poorly characterized. Here we describe the use of organelle electrophoresis to study the uptake of Mycobacterium bovis bacille Calmette Guerin (BCG) into murine macrophages. We demonstrate that live, but not dead, mycobacteria occupy a phagosome that can be physically separated from endosomal/lysosomal compartments. Biochemical analysis of purified mycobacterial phagosomes revealed the absence of endosomal/lysosomal markers LAMP-1 and β-hexosaminidase. Combining subcellular fractionation with two-dimensional gel electrophoresis, we found that a set of host proteins was present in phagosomes that were absent from endosomal/lysosomal compartments. The residence of mycobacteria in compartments outside the endosomal/lysosomal system may explain their persistence inside host cells and their sequestration from immune recognition. Furthermore, the approach described here may contribute to an improved understanding of the molecular mechanisms that determine the intracellular fate of mycobacteria during infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3591731.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Characterization of the negative elements involved in silencing the bgl operon of Escherichia coli: possible roles for DNA gyrase, H-NS, and CRP–cAMP in regulation (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The bgl operon of Escherichia coli is rendered cryptic and uninducible in wild-type cells by the presence of DNA structural elements that negatively regulate transcription. We have carried out a detailed analysis of the sequences implicated in negative regulation. Fine-structure deletion analysis of the upstream sequences showed the presence of at least two elements involved in silencing the promoter. Chemical probing of genomic DNA in vivo showed that a region of dyad symmetry, present upstream of the promoter, is hypersensitive to KMnO4. The hypersensitive region detected corresponds to the potential cruciform structure implicated earlier in negative regulation. Enhancement of transcription from the wild-type promoter, observed in the presence of the gyrase inhibitor novobiocin, was absent in a mutant that carried point mutations in the inverted repeat. This observation suggests that the activation seen in a gyrase mutant is mediated by destabilization of the cruciform because of reduced supercoiling. Deletion of sequences downstream of the potential cruciform also resulted in an increase in transcription, indicating the presence of a second regulatory element. Measurement of transcription from the bgl promoter carrying the deletion, in a strain that has a mutation in the hns gene, indicated that this region is likely to be involved in binding to H-NS or a protein regulated by H-NS, which acts as a non-specific repressor. We also provide evidence which suggests that transcriptional activation by mutations at the cAMP receptor protein (CRP)-binding site is mediated partly by antagonization of the negative effect of H-NS by CRP–cAMP as a result of its increased affinity for the mutant site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3621725.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Neisseria gonorrhoeae reverse transcriptase activity does not mediate pilin gene conversion (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3681707.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Action at a distance for glp repressor control of glpTQ transcription in Escherichia coli K-12 (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The adjacent, divergently transcribed glpACB and glpTQ operons of Escherichia coli encode the anaerobic glycerol 3-phosphate dehydrogenase and glycerol 3-phosphate transporter/phosphodiesterase, respectively. These operons are negatively controlled by glp repressor binding to operators that overlap the glpA promoter elements. Using DNase I footprinting, three additional operators (OT1–3) were identified at positions +307 to +359 within the glpT coding region. To assess a potential regulatory role for these remote operators in vivo, a glpT–lacZ transcriptional fusion containing all of the glpA and glpT operators was constructed. The response of this fusion to the glp repressor was compared to fusion constructs in which OT1 and OT3 were inactivated, either by deletion or by site-directed mutagenesis. It was found that repression of glpT conferred by binding of glp repressor to glpA operators was increased about three- to fourfold upon introduction of the remote glpT operators. In addition, two integration host factor (IHF) binding sites were identified downstream of the glpT transcriptional start site at positions +15 to +51 and +193 to +227. A regulatory role for IHF was demonstrated by showing that repression of glpT mediated by GlpR was decreased about twofold in strains deficient in IHF and that mutations in IHF1 and/or IHF2 decreased repression about two- to threefold. The effect of IHF was apparent only when the remote operators were present. All of the results are consistent with a model of repression involving GlpR binding simultaneously to the glpA and remote glpT operators, with intervening DNA forming a loop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3651733.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Polypeptide chain release factors (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Newly synthesized polypeptide chains are released from peptidyl-tRNA when the ribosome encounters a stop signal on mRNA. Extra-ribosomal proteins (release factors) play an essential role in this process. Although the termination process was first discovered in the late 1960s, much of the mechanism has remained obscure. However, important steps have recently been made in both prokaryotic and eukaryotic organisms in unlocking the secrets of this vital stage in protein synthesis. In this review we summarize these advances and focus attention on the remaining areas of uncertainty, particularly with respect to the models that have been proposed for the action of the GTP-hydrolysing termination factors in prokaryotes and eukaryotes, i.e. RF3 and eRF3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3711734.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Ssa1p chaperone interacts with the guanine nucleotide exchange factor of ras Cdc25p and controls the cAMP pathway in Saccharomyces cerevisiae (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have found that the guanine nucleotide exchange factor for ras, Cdc25p, interacts with Ssa1p in Saccharomyces cerevisiae. This interaction was observed with GST-fused Cdc25p polypeptides and confirmed by co-immunoprecipitation with the endogenous Cdc25p. Hsp82 appeared also to be co-immunoprecipitated with Cdc25p, albeit to a lower level than Hsp70. In a strain deleted for SSA1 and SSA2, we observed a reduced cellular content of Cdc25p. Consistent with a reduced activity of the cAMP-dependent PKA pathway, the rate of accumulation of both trehalose and glycogen was stimulated in the ssa-deleted strain. Expression of SSA1 reversed these effects, whereas co-expression of SSA1 and PDE2 restored high accumulation. The expression of genes repressed by cAMP, GAC1 and TPS1, fused to β-galactosidase, was also stimulated by deletion of SSA genes. The effect of ssa deletion on glycogen accumulation was lost in a strain deleted for CDC25 rescued by the RAS2ile152 allele. Altogether, these results lead to the conclusion that Ssa1p positively controls the cAMP pathway through Cdc25p. We propose that this connection plays a critical role in the adaptation of cells to stress conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01118.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    D-Erythroascorbic acid is an important antioxidant molecule in Saccharomyces cerevisiae (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: D-Arabinono-1,4-lactone oxidase catalysing the final step of D-erythroascorbic acid biosynthesis was purified from the mitochondrial fraction of Saccharomyces cerevisiae. Based on the amino acid sequence analysis of the enzyme, an unknown open reading frame (ORF), YML086C, was identified as the ALO1 gene encoding the enzyme. The ORF of ALO1 encoded a polypeptide consisting of 526 amino acids with a calculated molecular mass of 59 493 Da. The deduced amino acid sequence of the enzyme shared 32% and 21% identity with that of L-gulono-1,4-lactone oxidase from rat and L-galactono-1,4-lactone dehydrogenase from cauliflower, respectively, and contained a putative transmembrane segment and a covalent FAD binding site. Blot hybridization analyses showed that a single copy of the gene was present in the yeast genome and that mRNA of the ALO1 gene was 1.8 kb in size. In the alo1 mutants, D-erythroascorbic acid and the activity of D-arabinono-1,4-lactone oxidase could not be detected. The intracellular concentration of D-erythroascorbic acid and the enzyme activity increased up to 6.9-fold and 7.3-fold, respectively, in the transformant cells carrying ALO1 in multicopy plasmid. The alo1 mutants showed increased sensitivity towards oxidative stress, but overexpression of ALO1 made the cells more resistant to oxidative stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01133.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Using the yeast two-hybrid system to identify human epithelial cell proteins that bind gonococcal Opa proteins: intracellular gonococci bind pyruvate kinase via their Opa proteins and require host pyruvate for growth (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Neisseria gonorrhoeae opacity-associated (Opa) proteins are a family of outer membrane proteins involved in gonococcal adherence to and invasion of human cells. We wanted to identify additional roles for Opa in the infectious process and used the yeast two-hybrid system to identify human epithelial cell proteins that interact with Opa proteins. Although this system has been used successfully to identify many types of interacting proteins, it has not been used to screen a human cell cDNA library for binding partners of a prokaryotic outer membrane protein. Therefore, we were also interested in exploring the versatility of the yeast two-hybrid system in identifying bacteria–host interactions. Using OpaP from strain F62SF as bait, we screened a HeLa cell cDNA library for Opa-interacting proteins (OIPs). We identified five different OIPs, designated OIP1–OIP5, two of which are homologous to human proteins — thyroid hormone receptor interacting protein (TRIP6) and pyruvate kinase isoenzyme M2 (PK). In the studies presented here, we investigated the interaction between Opa proteins and PK in more depth. Opa–PK interactions were confirmed by in vitro and in vivo assays independent of the yeast two-hybrid system. Escherichia coli expressing six different Opa proteins from gonococcal strain FA1090 all bound more PK than Opa-negative E. coli in in vitro binding assays. Using anti-PK antibody and fluorescence microscopy, we showed that human epithelial cell PK co-localizes with intracellular Opa+ gonococci and E. coli expressing Opa proteins. Using a mutant of N. gonorrhoeae unable to grow on pyruvate or lactate, it appears that intracellular pyruvate is essential for gonococcal growth and survival. These results suggest a novel mechanism in bacterial pathogenesis, i.e. the requirement for direct molecular interaction with a host metabolic enzyme (PK) for the acquisition of an essential intracellular carbon source and growth substrate (pyruvate). These results demonstrate that the yeast two-hybrid system is a valuable tool for identifying biologically relevant interactions between bacteria and host proteins, providing valuable leads for further investigations into novel mechanisms of bacterial pathogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00670.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Transcriptional and post-transcriptional regulation by nickel of sodN gene encoding nickel-containing superoxide dismutase from Streptomyces coelicolor Müller (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A novel type of superoxide dismutase containing nickel as a cofactor (NiSOD) has been discovered in several Streptomyces spp. The gene for NiSOD (sodN ) was cloned from S. coelicolor Müller using degenerate oligonucleotide probes designed from the N-terminal peptide sequence of the purified enzyme. It encodes a polypeptide of 131 amino acids (14703 Da), without any apparent sequence similarity to other known proteins. The N-terminus of the purified NiSOD was located 14 amino acids downstream from the initiation codon of the deduced open reading frame (ORF), indicating the involvement of protein processing. The molecular mass of the processed polypeptide was predicted to be 13201 Da, in close agreement with that of the purified NiSOD (13.4 kDa). The transcription start site of the sodN gene was determined by S1 mapping and primer extension analysis. Ni2+ regulates the synthesis of NiSOD polypeptide. S1 mapping of both 5′ and 3′ ends of sodN mRNA revealed that Ni2+ increased the level of monocistronic sodN mRNA by more than ninefold without changing its half-life, thus demonstrating that Ni2+ regulates transcription. Both precursor and processed NiSOD polypeptides with little SOD activity were produced from the cloned sodN gene in S. lividans in the absence of sufficient Ni2+; however, on addition of Ni2+, active NiSOD consisting of only processed polypeptide was formed. Expression of the full-length sodN gene in E. coli produced NiSOD polypeptide without any SOD activity even in the presence of Ni2+. However, deletion of nucleotides encoding the N-terminal 14 amino acids from the sodN gene allowed the production of active NiSOD in E. coli, indicating that N-terminal processing is required to produce active NiSOD. These results reveal the unique role of nickel as a multifaceted regulator in S. coelicolor controlling sodN transcription and protein processing, as well as acting as a catalytic cofactor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00674.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Anaerobic regulation of the Escherichia coli dmsABC operon requires the molybdate-responsive regulator ModE (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Expression of the Escherichia coli dmsABC operon that encodes a molybdenum-containing DMSO/TMAO reductase is increased in response to anaerobiosis and repressed by nitrate. These changes are mediated by the transcription factors Fnr and NarL respectively. Interestingly, modC strains that are defective in molybdate uptake exhibit impaired anaerobic induction and no nitrate-dependent repression of the dmsABC operon. To determine if the molybdate-responsive transcription factor ModE is involved in this process, a set of dmsA–lacZ operon fusions were constructed and analysed. The pattern of dmsA–lacZ expression in response to anaerobiosis and nitrate addition was identical in both modC and modE strains, thus suggesting a regulatory role for ModE. In vitro studies confirmed that ModE bound the dmsA promoter at a high-affinity site typical of other E. coli ModE operator sites. Mutations in this site abolished ModE binding in vitro and displayed the same phenotype as a modE mutation. In contrast to previously characterized ModE operator sites, which either overlap or are located immediately upstream of the ModE-regulated promoter, the ModE site is centred 52.5 bp downstream of the major dmsA transcript start site. We identified a putative integration host factor (IHF) binding site in the intervening sequence, and in vitro studies confirmed that IHF bound this site with high affinity. Using himA mutants, we confirmed that IHF plays a role in the molybdate-dependent regulation of dmsA–lacZ expression in vivo. This study provides the first example in which ModE affects gene regulation in concert with another transcription factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00675.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Formation of oligomeric rings by XcpQ and PilQ, which are involved in protein transport across the outer membrane of Pseudomonas aeruginosa (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Pseudomonas aeruginosa is able to translocate proteins across both membranes of the cell envelope. Many of these proteins are transported via the type II secretion pathway and adopt their tertiary conformation in the periplasm, which implies the presence of a large transport channel in the outer membrane. The outer membrane protein, XcpQ, which is involved in transport of folded proteins across the outer membrane of P. aeruginosa, was purified as a highly stable homomultimer. Insertion and deletion mutagenesis of xcpQ revealed that the C-terminal part of XcpQ is sufficient for the formation of the multimer. However, linker insertions in the N-terminal part can disturb complex formation completely. Furthermore, complex formation is strictly correlated with lethality, caused by overexpression of xcpQ. Electron microscopic evaluation of the XcpQ multimers revealed large, ring-shaped structures with an apparent central cavity of 95 Å. Purified PilQ, a homologue of XcpQ involved in the biogenesis of type IV pili, formed similar structures. However, the apparent cavity formed by PilQ was somewhat smaller, 53 Å. The size of this cavity could allow for the transport of intact type IV pili.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00677.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Type II protein secretion by Pseudomonas aeruginosa: genetic suppression of a conditional mutation in the pilin-like component XcpT by the cytoplasmic component XcpR (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Pseudomonas aeruginosa exports a number of hydrolytic enzymes and toxins using the type II or general secretion pathway, found in a variety of Gram-negative bacteria and requiring the functions of at least 12 gene products (XcpP–Z and PilD/XcpA in P. aeruginosa). A number of these gene products are homologues of components of the type IV pilus biogenesis system, including four proteins, XcpT–W, which are highly similar to the pilin subunit in their size, localization and post-translational modifications. These proteins, in addition to the pilin subunit, are cleaved and methylated by the PilD/XcpA prepilin peptidase, but their interactions with other components of the export apparatus are unclear. Using a medium developed for the selection of export-proficient P. aeruginosa strains, we have isolated temperature-sensitive mutations in the xcpT gene and extragenic suppressors for one of the mutants. These suppressors fall into two classes, one that maps outside of the xcpP–Z gene cluster and may define additional cellular functions that are required for export, and a second that maps to the xcpR gene product and indicates a potential protein–protein interaction connecting two different cellular compartments and required for the assembly or function of the export apparatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00679.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    The σS level in starving Escherichia coli cells increases solely as a result of its increased stability, despite decreased synthesis (1997)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The σS level in starving (stationary phase) Escherichia coli cells increases four- to sixfold following growth in a defined or a complex medium. Chemostat-grown cells, subjected to increasing carbon starvation, also become progressively richer in σS content. These increases occur despite reduced transcription of the σS-encoding gene, rpoS, and translation of rpoS mRNA, and result solely from a large increase in the stability of the sigma protein. Previous results, based on rpoS ::lacZ transcriptional and translational fusions, and on methionine incorporation in σS, had suggested increased synthesis of σS in starving cells. Alternative explanations for these results consistent with the conclusions of this paper are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3961742.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Differential roles of homologous recombination pathways in Neisseria gonorrhoeae pilin antigenic variation, DNA transformation and DNA repair (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Neisseria gonorrhoeae (Gc) pili undergo antigenic variation when the amino acid sequence of the pilin protein is changed, aiding in immune avoidance and altering pilus expression. Pilin antigenic variation occurs by RecA-dependent unidirectional transfer of DNA sequences from a silent pilin locus to the expressed pilin gene through high-frequency recombination events that occur at limited regions of homology. We show that the Gc recQ and recO genes are essential for pilin antigenic and phase variation and DNA repair but are not involved in natural DNA transformation. This suggests that a RecF-like pathway of recombination exists in Gc. In addition, mutations in the Gc recB, recC or recD genes revealed that a Gc RecBCD pathway also exists and is involved in DNA transformation and DNA repair but not in pilin antigenic variation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01089.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Role of fimbriae-mediated adherence for neutrophil migration across Escherichia coli-infected epithelial cell layers (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: This study examined the role of P and type 1 fimbriae for neutrophil migration across Escherichia coli-infected uroepithelial cell layers in vitro and for neutrophil recruitment to the urinary tract in vivo. Recombinant E. coli K-12 strains differing in P or type 1 fimbrial expression were used to infect confluent epithelial layers on the underside of transwell inserts. Neutrophils were added to the upper well, and their passage across the epithelial cell layers was quantified. Infection with the P- and type 1-fimbriated recombinant E. coli strains stimulated neutrophil migration to the same extent as a fully virulent clinical E. coli isolate, but the isogenic non-fimbriated vector control strains had no stimulatory effect. The enhancement of neutrophil migration was adhesion dependent; it was inhibited by soluble receptor analogues blocking the binding of P fimbriae to the globoseries of glycosphingolipids or of type 1 fimbriae to mannosylated glycoprotein receptors. P- and type 1-fimbriated E. coli triggered higher interleukin (IL) 8 secretion and expression of functional IL-8 receptors than non-fimbriated controls, and the increase in neutrophil migration across infected cell layers was inhibited by anti-IL-8 antibodies. In a mouse infection model, P- or type 1-fimbriated E. coli stimulated higher chemokine (MIP-2) and neutrophil responses than the non-fimbriated vector controls. The results demonstrated that transformation with the pap or fim DNA sequences is sufficient to convert an E. coli K-12 strain to a host response inducer, and that fimbriation enhances neutrophil recruitment in vitro and in vivo. Epithelial chemokine production provides a molecular link between the fimbriated bacteria that adhere to epithelial cells and tissue inflammation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01104.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Intracellular expression of the ADP-ribosyltransferase domain of Pseudomonas exoenzyme S is cytotoxic to eukaryotic cells (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Exoenzyme S of Pseudomonas aeruginosa is an ADP-ribosyltransferase, which is secreted via a type III-dependent secretion mechanism and has been demonstrated to exert cytotoxic effects on eukaryotic cells. Alignment studies predict that the amino-terminus of exoenzyme S has limited primary amino acid homology with the YopE cytotoxin of Yersinia, while biochemical studies have localized the FAS-dependent ADP-ribosyltransferase activity to the carboxyl-terminus. Thus, exoenzyme S could interfere with host cell physiology via several independent mechanisms. The goal of this study was to define the role of the ADP-ribosyltransferase domain in the modulation of eukaryotic cell physiology. The carboxyl-terminal 222 amino acids of exoenzyme S, which represent the FAS-dependent ADP-ribosyltransferase domain (termed ΔN222), and a point mutant, ΔN222-E381A, which possesses a 2000-fold reduction in the capacity to ADP-ribosylate, were transiently expressed in eukaryotic cells under the control of the immediate early CMV promoter. Lysates from cells transfected with ΔN222 expressed ADP-ribosyltransferase activity. Co-transfection of ΔN222, but not ΔN222-E381A, resulted in a decrease in the steady-state levels of two reporter proteins, green fluorescent protein and luciferase, in both CHO and Vero cells. In addition, transfection with ΔN222 resulted in a greater percentage of cells staining with trypan blue than when cells were transfected with either ΔN222-E381A or control plasmid. Together, these data indicate that expression of the ADP-ribosyltransferase domain of exoenzyme S is cytotoxic to eukaryotic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01106.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Cloning of the mating type loci from Pyrenopeziza brassicae reveals the presence of a novel mating type gene within a discomycete MAT 1-2 locus encoding a putative metallothionein-like protein (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The mating type loci were cloned from Pyrenopeziza brassicae by chromosome walking from a mating type-linked polymerase chain reaction (PCR) fragment and shown to be idiomorphic by sequence analysis. The MAT 1-1 locus is approximately 3.2 kb and contains a single gene encoding a putative high-mobility group (HMG) domain protein. The MAT 1-2 locus is approximately 3.9 kb with three open reading frames (ORFs) encoding a putative HMG domain, an α-1 domain and metallothionein-like proteins. The putative α-1 domain ORF on MAT 1-2 is transcribed in the opposite orientation to the other two transcripts and extends into non-idiomorphic sequence. This is the first report of sequence analysis of the mating type loci from a discomycete fungus, which has revealed an interesting mating type infrastructure within the MAT 1-2 locus. Although metallothionein-like proteins have been implicated in a number of processes in animals and plants, they have not to date been implicated in the mating process of filamentous fungi. Possible roles for metallothionein-like proteins in the mating process are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01112.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Requirement of the VanY and VanX D,D-peptidases for glycopeptide resistance in enterococci (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Transposon Tn1546 confers resistance to glycopeptide antibiotics in enterococci and encodes two D,D-peptidases (VanX and VanY) in addition to the enzymes for the synthesis of D-alanyl-D-lactate (D-Ala-D-Lac). VanY was produced in the baculovirus expression system and purified as a proteolytic fragment that lacked the putative N-terminal membrane anchor of the protein. The enzyme was a Zn2+-dependent D,D-carboxypeptidase that cleaved the C-terminal residue of peptidoglycan precursors ending in R-D-Ala-D-Ala or R-D-Ala-D-Lac but not the dipeptide D-Ala-D-Ala. The specificity constants kcat/Km were 17- to 67-fold higher for substrates ending in the R-D-Ala-D-Ala target of glycopeptides. In Enterococcus faecalis, VanY was present in membrane and cytoplasmic fractions, produced UDP-MurNAc-tetrapeptide from cytoplasmic peptidoglycan precursors and was required for high-level glycopeptide resistance in a medium supplemented with D-Ala. The enzyme could not replace the VanX D,D-dipeptidase for the expression of glycopeptide resistance but a G237D substitution in the host D-Ala:D-Ala ligase restored resistance in a vanX null mutant. Deletion of the membrane anchor of VanY led to an active D,D-carboxypeptidase exclusively located in the cytoplasmic fraction that did not contribute to glycopeptide resistance in a D-Ala-containing medium. Thus, VanX and VanY had non-overlapping functions involving the hydrolysis of D-Ala-D-Ala and the removal of D-Ala from membrane-bound lipid intermediates respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01114.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    New tools in an old trade: CS1 pilus morphogenesis (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: CS1 pili serve as the prototype for a large class of serologically distinct pili associated with enterotoxigenic Escherichia coli that cause diarrhoea in humans. The four genes essential for CS1 pilus morphogenesis, cooB, A, C and D, are arranged in an operon and encode structural and assembly proteins unlike those of other pilus systems commonly associated with Gram-negative bacteria. CS1 pili are composed primarily of the major pilin subunit, CooA, which determines the serological type of the pilus. The major pilin subunit is assembled into pili by the proteins CooB, CooC and CooD. CooD is both a minor component found at the pilus tip and an essential assembly protein, whereas CooC is an outer membrane protein thought to be involved in pilin transport. CooB is a novel periplasmic chaperone-like protein that forms intermolecular complexes with and stabilizes the major and minor pilins. Unlike other pilin chaperones, CooB also stabilizes the outer membrane component of the assembly system, CooC. The proteins of CS1 pili have no significant homology to those of the well-characterized Pap (pyelonephritis-associated) pili and related systems, although most of the features of pilus morphogenesis are similar. Therefore, these appear to be among the rare cases of convergent evolution. Thus, for CS1 pili, enterotoxigenic E. coli use new protein ‘tools’ in the old ‘trade’ of forming functional pili.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01088.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Fatal attraction of mammalian cells to Legionella pneumophila (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Legionella pneumophila is a protozoan parasite that causes Legionnaires' disease. Its ability to do so is dependent on its capacity to replicate intracellularly within a phagosome that is not trafficked through the endosomal–lysosomal pathway and is surrounded by the rough endoplasmic reticulum. Within this unique niche, the bacterium undergoes alterations in gene expression. In addition, many virulence-related phenotypes that are induced in vitro by starvation are expressed intracellularly as the bacteria exit the logarithmic growth phase. (p)ppGpp appears to signal expression of the virulence-related genes in L. pneumophila upon starvation. This growth phase-dependent phenotypical transition is concomitant with lysis of the host cell, in which both necrosis and apoptosis seem to play roles. Many genetic loci that are required for intracellular replication within mammalian and protozoan cells have been identified, and the majority of them are novel. Two secretion systems have been identified, one of which may be distantly related to type IV secretion systems. The other is a type II secretion system similar to the PilBCD piliation system of Pseudomonas aeruginosa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01092.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Protein-mediated DNA transfer into liposomes (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The transfer of a foreign genome into a bacterium by means of phage infection is a very efficient but poorly understood process. To analyse the mechanism of phage DNA transfer at a molecular level, we have reconstituted FhuA, the receptor for phage T5 in the outer membrane of Escherichia coli, into unilamellar vesicles made of natural phospholipids. Cryoelectron microscopy studies showed that the binding of the phage to FhuA triggered the transfer of its double-stranded DNA (121 000 bp) into the proteoliposomes. DNA was entrapped within vesicles with a diameter ranging from 70 to 150 nm. The DNA appeared to be densely packed, but its presence did not alter the morphology of the liposomes, suggesting no DNA–lipid interactions. These liposomes represent an attractive model system for studying the mechanisms of DNA transport and condensation. They may also serve as alternative vehicles for the transfer of foreign genes into eukaryotic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01107.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    A complex composed of SycN and YscB functions as a specific chaperone for YopN in Yersinia pestis (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Human pathogenic Yersinia resist host defences, in part through the expression and delivery of a set of plasmid-encoded virulence proteins termed Yops. A number of these Yops are exported from the bacteria directly into the cytoplasm of their eukaryotic host's cells upon contact with these cells. The secreted YopN protein (also known as LcrE) is required to block Yop secretion in the presence of calcium in vitro or before contact with a eukaryotic cell in vivo. In this study, we characterize the role of the tyeA, sycN and yscB gene products in the regulation of Yop secretion in Yersinia pestis. Mutants specifically defective in the expression of TyeA, SycN or YscB were no longer able to block Yop secretion in the presence of calcium. In addition, the secretion of YopN was specifically reduced in both the sycN and the yscB deletion mutants. Protein cross-linking and immunoprecipitation studies in conjunction with yeast two-hybrid analyses showed that SycN and YscB interact with one another to form a SycN/YscB complex. Yeast three-hybrid analyses demonstrated that the SycN/YscB complex, but not SycN or YscB alone, specifically associates with YopN. SycN and YscB share amino acid sequence similarity and structural similarities with the specific Yop chaperones SycE and SycH. Together, these results indicate that a complex composed of SycN and YscB functions as a specific chaperone for YopN in Y. pestis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01110.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    The FruA signal transduction protein provides a checkpoint for the temporal co-ordination of inter- cellular signals in Myxococcus xanthus development (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: During fruiting body morphogenesis in Myxococcus xanthus, the intercellular C-signal induces aggregation, sporulation and developmental gene expression. To understand how a single signal system may induce temporally separated processes, we have focused on the class II gene, which codes for an essential component in the C-signal transduction pathway. We report that class II is identical to fruA and codes for a DNA binding response regulator. Transcription of fruA is developmentally regulated and depends on the early acting intercellular A- and E-signals. However, fruA transcription is independent of C-signal. Rather, genetic evidence suggests that C-signal controls FruA activity post-translationally. Genetic evidence strongly indicates that FruA is activated by phosphorylation. We propose that C-signalling results in the phosphorylation of FruA, thus activating FruA to interact with downstream targets. In the motility branch of the C-signalling pathway, FruA interacts with the Frz motility system; in the sporulation branch, we show that FruA is required for transcription of the sporulation locus devRS. On the basis of the two levels of control of FruA activity, we propose that FruA serves as a control point for the temporal co-ordination of intercellular signals during M. xanthus development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01113.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Translational control of mRNA processing in the F1845 fimbrial operon of Escherichia coli (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Endoribonucleolytic processing followed by differential decay of the cleavage products is an increasingly recognized mechanism for achieving co-ordinate regulation of functionally related proteins encoded by bacterial polycistronic transcripts. Unlike most examples when RNases E or III initiate decay, the daa transcript encoding F1845 fimbriae, a member of the Dr family of adhesins in Escherichia coli, is processed by an as yet unidentified endoribonuclease using a unique recognition mechanism. An open reading frame (ORF) predicted to encode a 57-amino-acid polypeptide was identified flanking the daa processing site. To determine whether this ORF is involved in processing, site-directed mutagenesis was used to generate mutants with altered translational efficiencies. A mutation in the putative ribosome binding site preceding the ORF significantly inhibited processing while the introduction of a premature stop codon abolished processing. Site-directed mutagenesis was used to introduce a limited number of mutations into the ORF, designated daaP, to alter the reading frame such that a different polypeptide of a similar size was encoded. Despite the presumed presence of trafficking ribosomes, this mutant failed to be processed, suggesting that the sequence of the DaaP peptide is important. However, the failure of a wild-type copy of the daaP gene to complement these mutations in trans suggested that the presence of wild-type daaP gene product was not sufficient to promote processing. Although active translation has been found to inhibit processing by RNases E and III, our data suggest that translation of the daaP gene is required in cis to promote processing by the endonuclease, perhaps due to an interaction of the nascent peptide with the ribosome or the daaP mRNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01117.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Replication at the telomeres of the Streptomyces linear plasmid pSLA2 (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Streptomyces linear plasmid pSLA2 initiates DNA replication bidirectionally towards its telomeres from a site located near the centre of the molecule; at the telomeres, the recessed ends of lagging strands are filled in by non-displacing DNA synthesis. Here, we report experiments that test three proposed mechanisms for lagging-strand fill-in. We present data inconsistent with recombinational or terminal hairpin models for the formation of full-length duplex pSLA2 DNA. Instead, we find that deletions in short, distantly separated homologous palindromes in the leading-strand 3′ overhang prevent propagation of linear pSLA2 DNA, implicating a mechanism of palindrome-mediated leading-strand fold-back in telomere replication. We further show that circularized pSLA2 DNA molecules are opened in vivo precisely at the terminal nucleotides of telomeres, generating functional linear replicons containing native telomeres covalently bound to a protein at their 5′ DNA termini. Together, our results support a model in which pairing of multiple widely separated pSLA2 palindromes anchors the 3′ end of the leading-strand overhang to a site near the overhang's base — providing a recognition site for terminal-protein-primed DNA synthesis and subsequent endonucleolytic processing. Thus, the replication of Streptomyces plasmid telomeres may have features in common with the mechanism proposed for telomere replication in autonomous parvoviruses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00838.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    A newly identified regulator is required for virulence and toxin production in Pseudomonas syringae (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The genes lemA (which we here redesignate gacS) and gacA encode members of a widely conserved two-component regulatory system. In Pseudomonas syringae strain B728a, gacS and gacA are required for lesion formation on bean, as well as for the production of protease and the toxin syringomycin. A gene, designated salA, was discovered that restored syringomycin production to a gacS mutant when present on a multiple-copy plasmid. Disruption of chromosomal salA resulted in loss of syringomycin production and lesion formation in laboratory assays. Sequence analysis of salA suggests that it encodes a protein with a DNA-binding motif but without other significant similarity to proteins in current databases. Chromosomal reporter fusions revealed that gacS and gacA positively regulate salA, that salA upregulates its own expression and that salA positively regulates the expression of a syringomycin biosynthetic gene, syrB. Loss of syringomycin production does not account for the salA mutant's attenuated pathogenicity, as a syrB mutant was found to retain full virulence. The salA gene did not similarly suppress the protease deficient phenotype of gacS mutants, nor were salA mutants affected for protease production. A gacS/gacA-dependent homoserine lactone activity as detected by bioassay was also unaffected by the disruption of salA. Thus, salA appears to encode a novel regulator that activates the expression of at least two separate genetic subsets of the gacS/gacA regulon, one pathway leading to syringomycin production and the other resulting in plant disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00842.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    The Bacillus SpoIIGA protein is targeted to sites of spore septum formation in a SpoIIE-independent manner (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The process of bacterial cell division involves the assembly of a complex of proteins at the site of septation that probably provides both the structural and the cytokinetic functions required for elaboration and closure of the septal annulus. During sporulation in Bacillus subtilis, this complex of proteins is modified by the inclusion of a sporulation-specific protein, SpoIIE, which plays a direct role in gene regulation and also has a genetically separable role in determining the gross structural properties of the specialized sporulation septum. We demonstrate by both green fluorescent protein (GFP) fusions and indirect immunofluorescence microscopy that SpoIIGA, a protein required for proteolytic cleavage of pro-σE, is also targeted to the sporulation septum. Septal localization of SpoIIGA–GFP occurred even in the structurally abnormal septum formed by a SpoIIE null mutant. We also report the isolation of a spoIIGA homologue from Bacillus megaterium, a species in which the cells are significantly larger than those of B. subtilis. We have exploited the physical dimensions of the B. megaterium sporangium, in conjunction with wide-field deconvolution microscopy, to construct three-dimensional projections of sporulating cells. These projections indicate that SpoIIGA–GFP is initially localized in an annulus at the septal periphery and is only later localized uniformly throughout the septa. Localization was also detected in a B. subtilis spo0H null strain that fails to construct a spore septum. We propose that SpoIIGA is sequestered in the septum by an interaction with components of the septation machinery and that this interaction begins before the construction of the asymmetric septum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00849.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    The rpfA gene of Xanthomonas campestris pathovar campestris, which is involved in the regulation of pathogenicity factor production, encodes an aconitase (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Xanthomonas campestris pv campestris (Xcc) is a plant pathogenic bacterium that controls the production of pathogenicity factors in part by a cluster of genes designated rpf (regulation of pathogenicity factors). Sequence analysis of one of these genes (rpfA) revealed an open reading frame with amino acid sequence similarity to aconitases from other bacteria. Aconitase activity was lower in cellular extracts of an rpfA::Tn5 mutant than in those from the wild type. A zymogram of aconitase activity after native gel electrophoresis showed the presence of two distinct aconitases in Xcc; the major aconitase was absent in the rpfA::Tn5 mutant. This mutant also had reduced levels of extracellular enzymes and extracellular polysaccharide (EPS). Supplying rpfA in trans to the rpfA::Tn5 mutant restored both the major aconitase activity and the synthesis of these pathogenicity factors. The transcription of the genes for two extracellular enzymes (prtA, encoding a serine protease, and engXCA, encoding endoglucanase) was reduced in the rpfA mutant background. Because some eukaryotic aconitases are also involved in iron regulation, we explored a possible connection between rpfA and iron metabolism. Intracellular iron levels in the mutants were lower than in the wild type as assessed by sensitivity to the iron-activated antibiotic, streptonigrin. Wild-type bacteria grown in iron-deficient conditions had a similar sensitivity to streptonigrin as the aconitase mutant. Overall, these results suggest that a prokaryotic aconitase can also act as a regulator of gene expression and that the regulation is possibly related to changes in intracellular iron levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00852.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    A fixed distance for separation of newly replicated copies of oriC in Bacillus subtilis: implications for co-ordination of chromosome segregation and cell division (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Spo0J protein of Bacillus subtilis is required for normal chromosome segregation and forms discrete subcellular assemblies closely associated with the oriC region of the chromosome. Here we show that duplication of Spo0J foci occurs early in the DNA replication cycle and that this requires the initiation of DNA replication at oriC but not elongation beyond the nearby STer sites. Soon after duplication, sister oriC/Spo0J foci move rapidly apart to achieve a fixed separation of about 0.7 μm, reminiscent of the segregation of eukaryotic chromosomes on the mitotic spindle. The magnitude of the fixed separation distance may explain how chromosome segregation is kept in close register with cell growth and the initiation mass for DNA replication. It could also explain how segregation can proceed accurately in the absence of cell division. The kinetics of focal separation suggest that one role of Spo0J protein may be to facilitate formation of separate sister oriC complexes that can be segregated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00857.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Identification of the Rhodobacter sphaeroides SOS box (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Gel-mobility shift assays with crude cell extracts of Rhodobacter sphaeroides, which belongs to the alpha group of the proteobacteria, have shown that a protein binds to the promoter of its recA gene, resulting in two retardation bands. Analysis of the minimal region of the R. sphaeroides recA gene required for the formation of the DNA–protein complexes, revealed the presence of the motifs GTTCN7GATC and GAACN7GAAC, which are centred at positions −21 and +8 from the transcriptional starting point respectively. Using PCR mutagenesis, we have demonstrated that these two motifs are required for the formation of both DNA–protein complexes in vitro as well as for the DNA damage-mediated inducibility of the recA gene in vivo. Furthermore, the level of the recA gene expression in the constitutive mutants is the same as that achieved by the wild-type cells after DNA damage, indicating that the binding protein must be a repressor. The motif GTTCN7GTTC is also present upstream of the R. sphaeroides uvrA promoter, which in vitro specifically binds to a protein and whose expression is DNA damage inducible. Mutagenesis of this motif abolishes both the binding of this protein to the uvrA promoter and the DNA damage-mediated expression of this gene. The fact that the recA and uvrA wild-type promoters compete with each other for the retardation band formation, but not with their mutant derivatives in any of these motifs, indicates that the same repressor binds to the operator of both genes. All these results lead us to propose the sequence GTTCN7GTTC as the SOS box of R. sphaeroides. This is the first SOS box known whose sequence is a direct repeat and not a palindrome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00860.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Recombinational exchanges at the capsular polysaccharide biosynthetic locus lead to frequent serotype changes among natural isolates of Streptococcus pneumoniae (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Serotype 19F variants of the major Spanish multiresistant serotype 23F clone of Streptococcus pneumoniae have been proposed to have arisen by recombinational exchanges at the capsular biosynthetic locus. Members of the Spanish multiresistant serotype 23F clone and the serotype 19F variants were confirmed to be essentially identical in overall genotype, as they were indistinguishable by REP-PCR, and had identical sequences at three polymorphic housekeeping genes. Eight serotype 19F variants were studied and all had large recombinational replacements at the capsular biosynthetic locus. In all cases, one of the recombinational cross-over points appeared to be upstream of dexBwhich flanks one end of the capsular locus, and in six of the variants the other cross-over point was downstream of aliA, which flanks the other end of the locus. In two strains a recombinational cross-over point between the introduced serotype 19F capsular region and that of the Spanish serotype 23F clone could be clearly identified, within cpsN in one strain and within cpsM in the other. The differences in the recombinational junctions and sequence polymorphisms within the introduced capsular genes, suggested that the eight serotype 19F variants emerged on at least four separate occasions. Changes in capsular type by recombination may therefore be relatively frequent in pneumococci and this has implications for the long-term efficacy of conjugate pneumococcal vaccines that will protect against only a limited number of serotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00658.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Regulated transcription of Clostridium difficile toxin genes (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Clostridium difficile toxA and toxB genes, encoding cytotoxic and enterotoxic proteins responsible for antibiotic-associated colitis and pseudomembranous colitis, were shown to be transcribed both from gene-specific promoters and from promoters of upstream genes. However, the gene-specific transcripts represented the majority of tox gene mRNAs. The 5′ ends of these mRNAs were shown to correspond to DNA sequences that had promoter activity when fused to the Escherichia coliβ-glucuronidase (gusA) gene and introduced into C. perfringens. The appearance of tox mRNA in C. difficile was repressed during exponential growth phase but increased substantially as cells entered stationary phase. When glucose or other rapidly metabolizable sugars were present in the medium, the stationary phase-associated induction was inhibited, indicating that the toxin genes are subject to a form of catabolite repression. This glucose effect was general to many toxinogenic strains having varying levels of toxin production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00663.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Plant-adapted green fluorescent protein is a versatile vital reporter for gene expression, protein localization and mitosis in the filamentous fungus, Aspergillus nidulans (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Green fluorescent protein (GFP) is a useful reporter to follow the in vivo behaviour of proteins, but the wild-type gfp gene does not function in many organisms, including many plants and filamentous fungi. We show that codon-modified forms of gfp, produced for use in plants, function effectively in Aspergillus nidulans both as gene expression reporters and as vital reporters for protein location. To demonstrate the use of these modified gfps as reporter genes we have used fluorescence to follow ethanol-induced GFP expression from the alcA promoter. Translational fusions with the modified gfp were used to follow protein location in living cells; plant ER-retention signals targeted GFP to the endoplasmic reticulum, whereas fusion to the GAL4 DNA-binding domain targeted it to the nucleus. Nuclear-targeted GFP allowed real-time observation of nuclear movement and division. These modified gfp genes should provide useful markers to follow gene expression, organelle behaviour and protein trafficking in real time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00664.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Cross-talk to the genes for Bacillus anthracis capsule synthesis by atxA, the gene encoding the frans-activator of anthrax toxin synthesis (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The two major virulence factors of Bacillus anthracis are the tripartite toxin and the polyglutamate capsule, which are encoded by genes on the large plasmids, pX01 and pX02, respectively. The genes atxA, located on pX01, and acpA, located on pX02, encode positive frans-acting proteins that are involved in bicarbonate-mediated regulation of toxin and capsule production, respectively. A derivative strain cured of pX01 produced less capsular substance than the parent strain harbouring both pX01 and pX02, and electroporation of the strain cured of pX01 with a plasmid containing the cloned atxA gene resulted in an increased level of capsule production. An acpA-null mutant was complemented by not only acpA but also the atxA gene. The cap region, which is essential for encapsulation, contains three genes capB, capC, and cap A, arranged in that order. The atxA gene stimulated capsule synthesis from the cloned cap region. Transcriptional analysis of cap by RNA slot-blot hybridization and primer-extension analysis revealed that atxA activated expression of cap in trans at the transcriptional level. These results indicate that cross-talk occurs, in which the pX01-located gene, atxA, activates transcription of the cap region genes located on pX02. We identified two major apparent transcriptional start sites, designated P1 and P2, located at positions 731 bp and 625 bp, respectively, upstream of the translation-initiation codon of capB. Transcription initiated from P1 and P2 was activated by both atxA and acpA, and activation appeared to be stimulated by bicarbonate. Deletion analysis of the upstream region of the cap
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3041667.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    DNA topology in hyperthermophilic archaea: reference states and their variation with growth phase, growth temperature, and temperature stresses (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In order to address the dynamics of DNA topology in hyperthermophilic archaea, we analysed the topological state of several plasmids recently discovered in Thermococcales and Sulfolobales. All of these plasmids were from relaxed to highly positively super-coiled in vitro, i.e. they exhibited a significant linking excess compared to the negatively supercoiled plasmids from mesophilic organisms (both Archaea and Bacteria). In the two archaeai orders, plasmid linking number (Lk) decreased as growth temperature was lowered from its optimal value, i.e. positively super-coiled plasmids were relaxed whereas relaxed plasmids became negatively supercoiled. Growth temperatures above the optimum correlated with higher positive supercoiling in Sulfolobales (Lk increase) but with relaxation of positive supercoils in Thermococcus sp. GE31. The topological variation of plasmid DNA isolated from cells at different growth phases were found to be species specific in both archaeai orders. In contrast, the direction of topological variation under temperature stress was the same, i.e. a heat shock correlated with an increase in plasmid positive supercoiling, whilst a cold shock induced negative supercoiling. The kinetics of these effects were analysed in Sulfolobales. In both temperature upshift (from 80 to 85C) and downshift (from 80 to 65C), a transient sharp variation of Lk occurred first, and then DNA supercoiling progressively reached levels typical of steady-state growth at the final temperature. These results indicate that DNA topology can change with physiological states and environmental modifications in hyperthermophilic archaea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3051668.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Cell-type specificity of the Anabaena fdxN-element rearrangement requires xisH and xisl (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The fdxN element, along with two other DNA elements, is excised from the chromosome during heterocyst differentiation in Anabaena sp. strain PCC 7120. Previous work showed that rearrangement of the fdxN element requires the xisF gene, which encodes a site-specific recombinase, and suggested that at least one other heterocyst-specific factor is involved. Here we report that the xisH and xisl genes are necessary for the heterocyst-specific excision of the fdxN element. Deletion of a 3.2 kb region downstream of the xisF gene blocked the fdxN-element rearrangement in hetero-cysts. The 3.2 kb deletion was complemented by the two overlapping genes xisH and xisl. Interestingly, extra copies of xlsHI on a replicating plasmid resulted in the xisF-dependent excision of the fdxN element in vegetative cells. Therefore, xisHI are involved in the control of cell-type specificity of the fdxN rearrangement. The xisHI genes had no effect on the two other DNA rearrangements. The xisHl-induced excision of the fdxN element produced strains lacking the element and demonstrates that the 55 kb element contains no essential genes. xisH and xisl do not show similarity to any known genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3081671.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Temperature-regulated mRNA accumulation and stabilization for fatty acid desaturase genes in the cyanobacterium Synechococcus sp. strain PCC 7002 (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Cyanobacteria acclimate to low-temperature conditions by desaturating their membrane lipids. The desB (ω3 desaturase) and desC (A9 desaturase) genes of Synechococcus sp. strain PCC 7002 were cloned and characterized, and the expression of the desA (Δ12 desaturase), desB and desC genes was studied as a function of temperature. The steady-state mRNA abundance for the desA gene was threefold higher in cells grown at 22 C than in cells grown at 38°C. des B transcripts were not detected at 38°C, but were abundant in cells grown at 22°C. Levels of desC mRNA were similar at both growth temperatures. The mRNA levels of each desaturase gene increased within 15min of a temperature shift-down to 22°C, and mRNA levels recovered within 15min after a shift-up to 38°C. The cold-induced accumulation of transcripts from the desA and desB genes was suppressed by the addition of chloramphenicol, but the transient elevation of the desC transcript levels at 22°C was not affected by chloramphenicol. The half-lives of the desA and desB mRNAs were significantly longer in cells grown at 22°C than in cells grown at 38°C, but the desC mRNA had a similar half-life at both temperatures. These studies reveal three patterns of temperature regulation for the desaturase genes, whose expression is tightly controlled by a combination of mRNA synthesis and stabilization. These studies demonstrate that elevation of desaturase mRNA levels is not the rate-limiting event during the low-temperature acclimation of cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3071676.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...